Well, I hate to be the bearer of bad news, but..........
what kind of pc monitor will support the Amiga 4000 ?
Depends what you mean by "support." The Amiga 4000 is capable of generating a 30khz video signal, which will be within the range of most standard VGA monitors. But this video mode is only available through software configuration of the A4000. So it only works in Workbench and things that are able to be mode promoted. Most games can't run in this mode. To be truely supported, you'll need either a scandoubler or a multi-sync (15 & 30khz capable) monitor. Both are rare and rather expensive, nowadays.
also does the a570 will work in the Amiga 4000 ?
No. Not in any logical way, at least. You may be able to disassemble the unit and use some parts of it, but I probably wouldn't recommend trying it.
the 4000 does not came with floppy disk , so i know that the floppy of the 4000 is different to the rest of the Amiga , so a normal pc floppy will work ??
No. You need an A4000 floppy drive. Or some combination of rare and expensive adaptors.