I've got an Intel Core Duo T2300 in my laptop (Lenovo 3000 N100, 0768-49G). Here is what I could find out about it:

$ sudo dmidecode 
# dmidecode 2.11
SMBIOS 2.4 present.
42 structures occupying 1436 bytes.
Table at 0x000DC010.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
        Vendor: LENOVO
        Version: 61ET37WW
        Release Date: 06/04/07
        Address: 0xE6B70

[...]
Handle 0x0002, DMI type 2, 8 bytes
Base Board Information
        Manufacturer: LENOVO
        Product Name: CAPELL VALLEY(NAPA) CRB
[...]

Handle 0x0004, DMI type 4, 35 bytes
Processor Information
    Socket Designation: U2E1
    Type: Central Processor
    Family: Other
    Manufacturer: Intel
    ID: E8 06 00 00 FF FB E9 BF
    Version: Genuine Intel(R) CPU           T2300  @ 1.66GHz
    Voltage: 3.3 V
    External Clock: 166 MHz
    Max Speed: 2048 MHz
    Current Speed: 1600 MHz
    Status: Populated, Enabled
    Upgrade: ZIF Socket
    L1 Cache Handle: 0x0005
    L2 Cache Handle: 0x0006
    L3 Cache Handle: Not Provided
    Serial Number: Not Specified
    Asset Tag: Not Specified
    Part Number: Not Specified

$ cat /proc/cpuinfo 
processor   : 0
vendor_id   : GenuineIntel
cpu family  : 6
model       : 14
model name  : Genuine Intel(R) CPU           T2300  @ 1.66GHz
stepping    : 8
microcode   : 0x39
cpu MHz     : 1000.000
cache size  : 2048 KB

I believe the chipset is "Mobile Intel 945GM Express", but I don't know how to verify it on a Linux system.

I'm not sure about the socket, but Intel claims "Sockets Supported: PBGA479, PPGA478". Now, I'd like to upgrade to the fastest compatible CPU available, but I'm a bit lost in all the details. Can you guys help me out with a couple of questions, please?

1. What CPUs can I choose from? (I think it's only the Core2Duo line, but it should be enough for an upgrade)
2. Can I use a 64-bit CPU?
3. Can I use a CPU with a higher FSB than 667 MHz?
4. Do I have to worry about additional cooling, or is it enough to check for similar voltage/TDP values?

Thank you!