Modem IRQs, password & mail problems

[Pigeon <jah.pigeon@ukonline.co.uk>]

A few small questions:

1) How do I tell Linux that my modem on /dev/ttyS2 wants to use IRQ5?
It's a non-PnP ISA hardware modem. At the moment I have to set it to
IRQ4, the default for the third serial port. I want to set it to IRQ5
to avoid conflict with stupid DOS/Windoze drivers that don't like
sharing serial port IRQs. man ttys and man mknod are silent on the
subject of IRQs.

2) I have a dead file somewhere that is interfering with some userid
stuff. Some of my directories give numerical user/group ids instead of
root or pigeon. exim refuses to start with "can't get user name for
userid x" errors, so no mail functions work. My /etc/passwd and
/etc/shadow seem to be OK; they contain the following (and also a
peculiar gnats/admin entry which I don't understand): (I haven't got
round to setting up shadow passwords yet)

root:onetwothreefour:0:0:root:/root:/bin/bash
pigeon:wedontwantyourbloodywar:1000:1000:Pigeon,,,:/home/pigeon:/bin/bash
gnats:*:41:41:Gnats Bug-Reporting System 
(admin):/var/lib/gnats/gnats-db:/bin/sh

Any ideas where I should be looking for the fault?

3) I want to use exim & mutt for mail, not staying online all the time
but dialling up with pon/poff to send and receive in batches. Can
anyone suggest the best howto / config tools for this particular
purpose?

4) Anyone recommend a good download manager for use with X/mozilla?

Thanks,

Pigeon