WRT compatible routers? or not?

So many questions...

1. What's the difference between OpenWRT and DD-WRT? Which one should I go for?

2. Do either support ADSL? as far as I see it is not listed as a feature. 

3. if ADSL is not supported - do I buy a WiFi-router and ADSL modem separately, install firmware on the router and try to make them work together?

4. Apparently finding a router that is supported by either Open or DD -WRT and is actually sold by amazon currently is impossible - at least for me. the list of supported routers is huge,  however any router I pick on amazon in the range of 30 to 100 quid is not supported. anyone got model names that can be bought these days that are actually supported?

5. should I even bother? maybe there is a great router which works with default firmware? i am open to suggestions =)