I think the answer there is yes, but I’m not sure what “I love her sailing” means in English 
Something to remember as well is that “caru” doesn’t map exactly on to the English “love”. It tends to mean actually to “love”, rather than be very fond of or really like something, whether cats or sailing
Thankyou, that does help. I got myself stuck in the habit of thinking that ‘dy garu di’ meant ‘loving you’ as opposed to ‘love you’. I was thinking that the literal translation if you like of ‘dw i’n dy garu di’ was ‘I be loving you’ rather than ‘I love you’.
Well you might ‘love her cat’ but be ‘loving her cat’ when you were stroking it, is the possible difference.
The other question is at what point should i concentrate on nailing the mutations, or should I continue ‘not worrying’ about it and allow myself to pick it up naturally
Certainly don’t concentrate on nailing them- talking and getting them wrong is far more important! Knowing when they can occur is in my opinion a good thing- it will allow you to notice them quicker when you hear them and thus pick up on them and see where they are, or are not, used by native speakers and thus use them similarly more quickly than if you didn’t. At least that was the case with me.
You can concentrate on nailing the mutations whenever you feel like - not by boring yourself or pressurising yourself, but just by being aware of them. If you’ve ever heard of mindfulness, you’ll have heard of the practice of being aware without judging - this is how to be with mutations. Hear that what you have said doesn’t follow the rules, or be aware that you are not sure whether there is a mutation or not (you can think about it / look it up / ask here later), but never say those natural put-downs (I’ll never get this right; I always get these wrong; Oh, my Welsh is so bad etc) that put you under pressure.
This as well. You are never permitted to worry…!
If you said “I love her acting!”, you would be happy with that, I think. It means, I think,“I love her way of doing this thing” or “her ability” “how she does this”. You could love the way she expertly sails her boat!! But it isn’t something one says all that often unless sailing is your number 1 activity!!! I suppose yn Gymraeg, I’d say, “Dwi caru shwd (sut) mae hi’n hwylio.”
Thank you for the advice. I like to think I’m mindful of mutations. Often I don’t have the spare mental capacity to consider them when listening or speaking. It is something that I do spend a little mental effort on, when going back to earlier material on this course for revision/ to re-do the longer sentences
I have "‘eisiau’ - to want "fairly hard wired into me, i pronounce this as spelled. Doing courses 1 & 2, I noticed that Aran & Catrin were pronouncing it differently to what I’m used to, but it was subtle and I did think it was the more Northern way of pronounciation. I had a look at the Level 1 pdf, and see it’s spelt ‘isio’ which matches more the pronunciation that Aran and Catrin use. Is it really exactly the same word or is there a difference?
It is the same word. Eisiau is the “proper” way to spell it, but over time the pronunciation has morphed a bit, and differently in north and south. Often now it is spelled as it is pronounced, rather than the original word. In the north, that is “isio” and in the south it is “isie”. With any of these pronunciations (including as originally spelled), you should be understood.
Exactly what Sionned said… 
In Challenges 1.11 and 1.12 south, (I can’t vouch for north, I haven’t checked) it becomes clear that, although gwbod is to know rhywbeth, nabod is to know rhywun, but if this was ever actually mentioned, I missed it. Was this deliberate or did a sentence or two get left out in transit between @aran and @Iestyn?
p.s. edited typo a day later!!
I honestly can’t actually remember whether the difference was clarified or whether it was left for us to pick up, either way it gets in there somehow. Sorry to answer with “I don’t know” but there you are. 
“nabod” is also to know a place btw. 
I thought it did, but had never been able to pin it down for certain.
Does anyone know if it maps well onto the French “connaitre” (as opposed to “savoir”), or German “kennen” (as opposed to “wissen”)?
i.e. Can it have a slightly wider application than just knowing a person or a place?
I’m fairly sure this is mentioned in Level 1 North, I shall check.
In Challenge 11, 24 minutes in, it mentions that gwbod is to know something, but nabod is to know a person.
I don’t know about the German but the French connaitre is used in the same way as nabod and also savoir as gwybod
I’ve just realised something. I remember being taught ‘Mi wnes i’ years ago, rather than just ‘wnes i’, this did confuse me as I wondered what the ‘mi’ was for. it’s a possessive, just like ‘dy garu di’, kind of like ‘I did’, yes?’. if so why did no-one tell me this before!
Too much grammar is a bad thing, this is why I like SSiW so much!
This “mi” or in the South “fe” has nothing to do with possessives. It is the same for every person and shows, that the sentences is an affirmative sentence, not a question. You can also say : "fe gei di " = you can, you’re allowed, or “mi naeth o” = he did. If you use it or not, is optional. Use, what sounds better for you.
Small addition to Brigitte’s answer: grammatically it is known as an affirmative marker.
Gareth King says it is a characteristic of spoken Welsh.
When used before a short form verb it causes soft mutation. However, it seems to cause it even when it’s not there, i.e. when it is “understood” which is why the affirmative statement short form is often mutated in speech, even though the “rule” for written Welsh says it shouldnt be .
e.g. wela i di / wela i chi - I’ll see you.
Thank you @brigitte and @mikeellwood. I’ve heard these mi/fe constructions over the years, and have never actually known what they were, apart from knowing I didn’t need to use them (and so I didn’t).
As @mikeellwood says, most (or all!) courses and grammars talk of them as something characteristic of spoken Welsh, which can be dropped leaving the soft mutation.
As @margaretnock implies, though, they are possibly far less common now ( than in an indeterminate past 
), so they are something which it is good to know about but not compulsory to use
Thanks for finding nabod in Level1.11 North!!
Re the use of mi or fe, would this explain something I thought i knew and have questioned since not finding it anywhere? I thought, “Wn i ddim” meant “I don’t know” and “Fe wn i” meant ,“I know!” (i.e. stressed). So, is “wn” from 'gwbod! and the ‘fe’ as described above??? Also, I thought I’d heard “Wn i” meaning “I know” in “Rownd a Rownd” and I can see someone could have just left off the ‘mi’, or even said it without me picking up on it as the same as 'fe".