is it good for a single person to live in Wroclaw as all the expenses will be on me
If it's 7700 after tax you'll be more than fine, especially since you're single, if you had to support a partner you'll probably struggle on it.
Rent for you is gonna be anything from 1200-2000 per month I reckon, depends on where. I'm not close to Wroclaw so I can't give advice.
I guess the company will not help me with the flat rent / accommodation or bank account creation
No harm in asking them to help you look for places, after all, they want you to relocate so they should help. As such a company, they surely have someone there to help foreigners settle.....They'll help with a bank account at least.
have a look on gumtree.pl...wroclaw....actually I'll get a link for you....
you need to search for 'mieszkania i domy do wynajecia' that's houses and apartments for rent.
re: working in IBM, In know nothing abhout the company other than they helped the Nazis during WWII