Ok my responses are as follows, just my opinion mind you!
1) Initially on low carb eating you loose a lot of water so rapid weight loss at first is common.
2) I don’t touch grapes now as they are quite a high carb fruit, these days I stick to berries, here’s a useful graphic:
https://www.dietdoctor.com/low-carb/fruits
And another one for nuts, cashews score high:
https://www.dietdoctor.com/low-carb/nuts
3) Metformin is not a quick acting drug so the timing isn’t crucial. I take three a day and used to spread them out evenly but was forgetting the midday one, so my GP suggested taking two in the morning and one in the evening. The usual advice is take the forgotten dose as soon as you remember but not if the next dose is due very soon. I think if you miss an evening dose, that anytime up til bedtime would be ok to take it, it doesn’t have to be exactly 12 hours apart.
4) I use coconut products a lot, oil, cream and flour. Here’s my favourite coconut recipe, it uses coconut cream and flour:
https://www.dietdoctor.com/recipes/keto-coconut-porridge
5) The dietitian will probably advise against LCHF but personally I have seen my cholesterol numbers improve after initially deteriorating. Rapid weight loss can cause cholesterol numbers to deteriorate initially.
6) My personal experience is identical to you, energy levels going down and down which I just put down to getting older and craving for sugary stuff. Now my energy levels are right back up I and don’t crave the junk I used to eat.
Phew! I feel like I’ve just written an exam paper!
No seriously, I hope that helps