1. yes you can. if you know enough.
2. if you have 10000punds/16000 euros to spend on engine, you dont have to worry about anything about price. you could just drive your car to local workshop and tell them to do all.
3. how much it will cost, depends on how much you can do by your self and where you buy them. look prices from burton, pj motorsport and such places. and how much labour cost is, it depents who builds your engine.