A change is as good as a holiday!

For your nose piercing, yep, you can definitely get it pierced and use sleeper-type jewellery from the beginning. Just be aware that depending on the shape of your nose, the piercer may have to pierce in a slightly different spot to get a ring to fit, itms? I can't wear sleeper-type jewellery in my nose piercing because it's too high up
What sort of jewellery were the previous studs? The ones I buy have a really long tail that's bent into an L shape so they're harder to dislodge... yeah, they still fall out at times but a lot less frequently than the straight retainer-style jewellery I used to wear.
(I'll PM you on FB and put you in touch with my favourite piercer, he's super-friendly and I'm sure will be more than happy to answer your questions and give you some advice - he likes to see successful piercings and happy piercees!)

As for your haaaiiirr... you're in for some fun and games, girl! Unfortunately, the colour strippers you can buy at places like Priceline don't do a damn thing to shift black... pretty much nothing does! I personally would say that bleaching is your best bet, particularly if you're DIYing it. Stop dyeing your hair NOW, let it grow out as long as you possibly can hold out, then do the bleaching in sessions over a period of weeks. For the first couple of sessions, you won't see a visible change (except at the roots, so keep a dark semi colour handy to fix them to match your ends), but trust me, you get there eventually. Luckily with the colour you want to go, you won't need to strip ALL the black out - not even close. All you need to do is lighten it just enough so that the new colour you want will take, itms... you're probably aiming for a mid-orangey-brown, not too light, but it must be a very visible change or the new colour won't take if there's too much black.
Gah, that makes no sense lol. It's 7:30am hahaha. Once you've stripped out the black, almost any colour will hold, except red and purple :P Them's the breaks! I'm using a dark pink/red atm and I have to redo it every 2-3 weeks to freshen the colour and fix the faded patches. Schwarzkopf does some really nice intense reds/purples that you can buy at supermarkets/chemists for decent prices, but I find I have to add a bit of water to the mix as it's very thick (and I have thick hair).
I'm sure a salon job would hold slightly better than supermarket dye, but I'm on a budget lol Good luck, hope some of that helps you work out how to go about it!