Edit: NM

I haven't run into any activations; I don't think PSN usage is high enough. Occassionally you will run into games (eg exit, I think) that will have free levels on PSN. I only got my PSP about 1 month ago.

No serial numbers or anything. One of the bigger anti-CFW complaints is that there is no way for Sony to restrict those with pirated games from playing MP.
And the size varies, but assume a maximum of 700 per disc, but likely a lot less. I think Megaman Legends (GREAT game) is only 300 megs.
If you rip your own, you'll probably need the whole ~700. But if you either do a bit of research, or grab some Scene Releases (of the games you legally own), a lot of the padding and other languages can be removed (like with any rip).

I use http://www.amazon.com/PhotoFast-CR-5400-MicroSD-Adapter-Dual/dp/B001I0T92Q with a single 8Gig MicroSDHC. Read all the comments before getting one; very good hints. The psp memory cards have come way down in price; but microsd is much more compatible with the next hobby I might pick up.
Oh yea - I bought my adapter off of ebay; I have had no problems but if you can find it at a store that is easily returnable it would be better (judging by some of the Amazon comments).

Ooh thats rather fancy, never knew they made adapters for memory stick. Shall have a hunt on ebay for one of those and a microsdhc. Cheers,

Upon rereading the amazon comments I did remember something; I was unable to use the adapter with the chickHEN hacking method. It would just hang; so you MIGHT have to get a small orignal Sony proDuo for the initial CFW setup. Once the CFW is setup, the adapter worked fine for me.

Would the problem be that its not an official memory stick or could the issue be the unusual dual card configuration?
Just done a bit more research on the issue and it seems to be because of the MagicGate tech on the memory card. Apparently when a PSP boots into service mode, it can only read data off a magicgate enabled memory stick, presumably the system can read memory sticks with more mundane gates in normal mode but it requires a gate +1 in service mode

I don't know - the official Sony memory sticks do use a technology called "magic gate' and this might affect it. I tried about 10x to flash using chickHEN with the card; it only took 1 when I used the orignal 32Meg Sony. After the CFW was installed the adapter with microsd has worked fine. I do have a fat PSP aka PSP-1000 so yours might behave differently.

Well I just got my PSP and aside from a tiny and easily ignored defect in the screen (looks like a small hair but doesn't come off) it seems to be good.
It seems I have firmware 5.50 which by the looks of things means I'm out of luck. I can find some info for modding the PSP1K & 2K with 5.5 but haven't found anything with the 3K. It also looks like I can't use ChickHEN and need a pandora battery which I'm assuming didn't come with it (its at least a sony branded battery).
The 32MB memory stick that came with it has an update file listed as "5.00 M33" but it says the data is corrupt, I presume this means someone tried to mod it but couldn't because it was a lower version
The information on modding is confusing at best though, can anyone clear up whether or not I'm stuffed in regards to modding? If so I might as well update to firmware 6.0 and be done with it

After a bit of googling, here's what I found...
http://www.dcemu.co.uk/vbulletin/showthread.php?t=224663
I have a modded PSP1k from the start, so I can't help you much - but I do know that the 3k is the toughest to mod, and can be picky. Get at least one 512MB (or more) Sony/SanDisk ProDuo stick with MagicGate on it to use with any possible modifications, just to be sure.

You can make your own Pandora battery, you know that? Just get another spare battery (you know, Just In Case) and try to roll your own.

Err yeah I'd just as soon NOT take a knife to the battery. Besides if I'm getting a spare battery that means spending money I can't afford and even if I could I might as well get a pre-made pandora and save myself the trouble.
Its not looking too likely that I can mod it at the moment but there was some mention of a custom firmware release at the end of the month so maybe...

Well then, just pay someone to do it for ye. There are tons of places out there that will let you send them your PSP and get it back hacked (or never see it again!), or there has to be some store that will do it for you. Well, there is for me, anyway.

Did you mis-read the part about my not wanting to spend more money?