Few questions before I try to install Ubuntu

[Boyan R.]

My 160 Gb HD is divided in 6 partitions. First four are occupied, 
but fifth (5 Gb) and sixth (2.7 Gb) are free (currently both in fat32).

I want to install Ubuntu on this 5 Gb partition. Should I manually format
it into linux format, and create swap partition (I have 512 Mb Ram) ?
So, basicely, should I split it to 4 Gb + 1 Gb swap manually, or when I
start installing Ubuntu (latest release) it will do that automaticly for me
?

Also, can Ubuntu fit on my 2.7 Gb partition ? (1.7 Gb + 1 Gb swap I guess)
I just want to see how it looks and works (for the start)

If I MUST create swap partition manually, should I make it exactly 1024 Mb,
or is it better to make it little larger (just in case) ?

Currently I have WinXP on my first and second partition. 
What boot manager uses Ubuntu, Grub, Lilo or something third ? 
I guess there is no risk of losing my current boot menu ?

Sorry about this idiotic questions, I hope somebody 
will find some time to answer me :(