1. how longs a piece of string? Depends where you want to invest, how much you have? how much you can rent it out for? Is the investment for capital appreciation or an income from rent? It's a case of researching the market and considering how much you can afford to invest etc
2. not sure what you mean - similar to UK if you've invested there. - lenght of time to buy depends on property buying - if new and off plans - when built or If in a chain etc. straight forward purchase no chain should take 4/6 weeks
3. see 1
4. not sure what you mean
5. See Oasis for stamp duty rates, tax issues on income received i suggest you check the Inland Revenue site.
Suggest a conveyancing solicitor or accountant will give you more specific advice certainly on the legal and tax issues