2006 Macbook Core Duo 2ghz upgrades

I'm trying to keep my old 13" 2006 Core Duo (not Core 2 Duo) 2ghz Macbook a little longer. Have 3 questions.

I'm currently running Snow Leopard. Can't upgrade to Lion right?

Upgraded my Ram to 2gb a few years ago. Is this the max?

Currently running a 320gb Seagate Momentus 7200rpm 16mb cache 3gb/s.
Can I upgrade to the new Seagate Hybrid drive with 750gb 7200rpm 32mb cache 6gb/s sata?

 

Thank you simsaladimbamba for your fast answers

The good thing about the hard drive upgrade is if I do replace my Macbook this year I can probably use the upgraded Seagate Hybrid drive ST750LX003 in the new Macbook Pro.

 

Yes my motherboards max Sata is 1.5gb/s. My current hard drive is downgraded to 1.5gb/s even though the hard drive is capable of 3gb/s.

I found a thread on Seagate site. It said that the drive auto recognizes the Sata chipset and should be able to go down to 1.5gb/s. There are some chipsets it will not recognize though such as VIA VT8237 Southbridge.

Is this the chipset in my Macbook 'Intel ICH7-M AHCI'? That's what I found in system profiles under Serial-ATA.

 

Well I got the Seagate Hybrid 750gb drive ST750LX003 today. And I installed it in my Macbook. Booted from my old drive in an external enclosure into my OS. I then formated the new hard drive. So my Macbook recognizes the hard drive Using Carbon Copy Cloner to clone my old drive to the new. I think this will take a few hours as I have about 140gb on there. Will update when I've tested the new drive (actually booting from it).

Update:
Seems to be working fine so far. Actual boot up time is 5 seconds faster (was 35sec, now 30sec) . I'm sure on a newer motherboard with sata 3gb/s or 6gb/s it would be an even better improvement. No issues at this point