newbie problems?

Hello everybody,
I'm a newbie for u-boot. I wanna port u-boot to a lubbock-like (pxa255) board, however I got some problems.
1, I don't understand what is TEXT_BASE mean in u-boot. My sdram start at 0xa0000000 and flash start at 0x00000000 in my board, so the TEXT_BASE seems to set 0xa0000000, is it correct?
2, Because I ported u-boot without using any BDI2000-like debugger, so there has anyother debugger methods for me.
3. Mybe, I shall study some extra references. Where can find it?

Thanks in advance!!

-- Eason