I think the cooled boiled water might be for eye wiping. Although I don't think I did that and doubt I will this time! And nappy changing is much easier when doing it in person!
I know it's a bit far in advance but baby led weaning is really simple - essentially baby eats what you do (with no honey till 1, a bit less salt, and make sure that there's nothing that they could choke on). Have a look at this book if you want to know about both methods (purees and baby led); the 'pure' baby led book is this one, but I found it a bit preachy (even though we did 100% BLW except when out and about, taking Ella's Kitchen pouches with us for ease which he could just suck out the pouch). The BLW book is this one; or the recipe book (which I preferred, and it still gives you an intro to BLW, although less in depth) is here. In fact, for those on mat leave, reading about weaning now is a good idea as you probably won't get as much opportunity to later!
Re nursing clothes, I did get a few, and I do recommend them, but only a few - once baby's older you'll be much more relaxed about the whole thing and be able to make do with more normal clothes.
I'm small (34B); go up to 34C/D maybe when milk comes in, then back down. I'm still wearing nursing bras from last time round. The bump band thing is a good idea, if you pull up a top to gain access it means your belly is still covered. Nursing specific stuff is also good, depending on how it's cut and how faffy it is. A cardigan / shawl / scarf is also a good idea if you're shy.