When my older two started school I had nametapes with just our surname on - it is fairly distinctive and in a small school I didn't care which child the clothes came back to. Now in senior school they have their shortened first names and surname. They are at different schools with similar uniforms and it can be a faff relabelling things for DS2 (if anything lasts that long).
DD designed her own nametapes first name, middle name and surname (9, 4, 6 characters and a little embroidered kitten). They take forever to sew on - I would go for as much brevity as possible in what you put on the nametape.
If you are very lazy you can pay someone to sew the labels on - there is a lady near me who does alterations and will nametape for me. Either way I'd say it is essential to sew all the way round to avoid garment and label parting company.
I think iron on labels only last a few washes, but some people obviously have more luck.
When DD was 3.5 and at nursery she had spare clothes every day. I think that is an essential in case of accidents and this included things like turning tap on too hard when washing hands. I would be surprised if school would not allow you to do this. DD is fairly fussy and would be horrified at wearing school spare pants - suspect both my DSs would have felt less bothered though. I have always donated outgrown pants to nursery/infant school though and would expect them to have a good supply if necessary.
I never give DD (now 6) a new item in her lunch without running it past her and getting an assurance it will be ok as when I have been experimental it's often at the expense of her eating it up. A lot of children have less nutritous lunches than her so as a compromise we now do crisps on a Friday providing lunch has been eaten sensibly through the week. She loves to pick out a packet for this. I generally freeze a juice carton and/or tube of yoghurt to help keep her lunch cool.