i386 or amd64 ?

[Panter V.]

Hello,

I have a AMD Sempron 2600+ 64 bit processor running on a soket 754 ECS 
motherboard 
(http://www.ecs.com.tw/ECSWeb/Products/ProductsDetail.aspx?DetailID=555&MenuID=21&LanID=9__)
_ 
<http://www.ecs.com.tw/ECSWeb/Products/ProductsDetail.aspx?DetailID=555&MenuID=21&LanID=9>_Computer 
has 256 DDRAM and I also want to connect 2 USB printers to it (a laser 
Xerox 3116 and an inkjet HP PSC 1110)

I want to use this computer as a development server and firewall. I will 
run Apache 2, PHP 5, MySQL, Samba, an FTP server ...
At a later time I would like to use this computer as a workstation as 
well and I will need KDE, OpenOffice 2, Thunderbird, Firefox, Eclipse ...

I have a few questions:

Can I use the amd64 version for this configuration?
If I use i386 does this mean performances will be visibly lower than 
using amd64?
Are the software and drivers I need 64 bit ready or will their 32 bit 
versions run at least as good as they would do on i386?
Which version do you recommend me to use i386 or amd64?

Thank you very much for your answers.

Panter.