[ubuntu] 32/64 bit? SWAP? Ubuntu 14.04 LTS on MacBook 3,1

Scenario:

I am a Linux newbie and I will be installing Ubuntu for the first time ever this weekend on my white MacBook 3,1 as a part of a triple boot rEFIT setup with Snow Leopard OSX, Windows 7, and Ubuntu.

Partition Goals:
Snow Leopard = bare bones/minimal install 5 - 10 GB, I will never use it
Win 7 = 80 GB, I use this for work: MS Word, excel, email, and skype
Ubuntu = 20 GB, I use this for personal email, web browsing, and to learn how to use Ubuntu!

Questions:
1. Do I choose the 32 bit or 64 bit version of Ubuntu?
2. Do I choose to make an extra SWAP partition for Ubuntu? Or do I choose to use a savefile instead?

Hardware Specs:

MacBook 3,1 (Late 2007)
Intel Core 2 Duo 2.0 GHz
4.0 GB RAM
120 GB Hard Drive, Serial ATA 5400 rpm
Intel GMA X3100 144 MB RAM (Graphics)
DVD+-RW
Integrated Airport Extreme 802.11a/b/g/n (draft-n enabled)
Gigabit Ethernet
Bluetooth 2.0 + EDR
2x USB 2.0
1x Firewire 400
1x Optical digital / analog audio line-in
1x Optical digital / analog audio line-out
iSight Camera
mini DVI

Software Specs:

Snow Leopard 10.6.8 OSx
Windows 7.1, Home Premium Edition, 32-bit
Ubuntu Trusty Tahr 14.04 LTS, 32/64 bit?

I am familiar with using computers, but I am beginner when it comes to hardware, drivers, software, and programming.. Thanks, meow!