I want an automatic or maybe hand wind watch for christmas, but a lot of newer model's i don't think will fit me, but whether that will change as i grow i don't know. But anyway, i have seen that vintage are usually smaller and should fit better. But I have a few questions.

What are some good, reputable brands that look nice and should work 99% of the time?

Are there any good reputable sellers, preferably uk?

What things can go wrong? Is running fast/slow, breaking, not waterproof at all and being damaged by a splash something to worry about?

I have seen vostok, hmt and a few seiko 5's but what other brands are good?

I have also seen a vostok 24 hour, are these any good or are there better 24 hour versions out there?

My budget is near £100, preferably lower than that but am willing to spend about max £10-£20 more

sorry for so many questions but i need to be sure that i should look for vintage, i worry alot.