New-Used eMac - Need udpate/upgrade advice

Hey.

As mentioned in a previous post, I just picked up a 800MHz eMac. Nice little machine. Ended up having a SuperDrive, so that is a plus. It is cute

So, couple of things I would like to upgrade, and could use some input.

1. OS.
- It has version 10.2.8
- What is best way to get it up to the latest version? My iBook has 10.4.10. Do I need to purchase an update? I have full install cd's and licenses with purchase.

2. RAM
- It only has 256MB. How much will this puppy take. I should like top up it to 1GB or more if it can take it (my iBook has 1.5GB, and that has worked out pretty good).

3. Networking
- Would like to get wireless in it as there will be no cable near where it will sit. What is best approach.... getting airport card, or an airport express, or...

Also, until I get the networking sorted out, and in case I need to dl the updates for OS, is there a way to share the wireless connection from my iBook to the eMac via firewire or ethernet cable (I dont have any crossover cables, just standards ones.

Thanks in advance.

eMac Specs:
800MHz G4
100MHz bus
256MB RAM
Super Drive
OS X Version 10.2.8

Had pretty much mentioned most of these specs...not sure what else could be needed. Let me know if I'm missing something...

Thanks.