Port Forwarding?

I want to port forward through two routers, a Dlink DI-634M and a Dlink DI-624 Rev. C. The internet (modem) is connected to the DI-634M and the DI-624 is connected to the DI-634M via a 100ft CAT-5E cable (not crossover). I want to be able to port forward from the first router to the second one, to my computer so I can play my games online. Please help me! Any help will be greatly appreciated.

Questions:
Can I disable DHCP on the 2nd router?
Do I have to change the IP address of the 2nd router to match the first?
Do I have to use a crossover patch cable to connect the 1st to the 2nd router?

First off let me explain to you my settings:

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DI-634M (1st) - Connected to internet

[LAN]

MAC Address : 00:17:9A:40:74:07
IP Address : 172.18.231.169
Subnet Mask : 255.255.255.0
DHCP Server : Enabled

[LAN Computers]

IP Address Name (if any) MAC
172.18.231.115 Adrian-PC 00:1f:bc:00:22:2e
172.18.231.136 DI-624 00:11:95:19:82:bf
172.18.231.152 tani 00:0c:6e:2f:e2:30

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DI-624 (2nd) - Connected to other router via 100ft CAT-5E cable (port 3 on first router to wan port on second router)

[LAN]

MAC Address: 00-11-95-19-82-be
IP Address: 192.168.0.1
Subnet Mask: 255.255.255.0
DHCP Server: Disabled

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Computer - IP address manually configured

[LAN]

IP Address: 192.168.0.100
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.0.1
Preferred DNS Server: 192.168.0.1

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Now onto my problem, when I disconnected the CAT-5E cable and plugged it into the LAN port 1 on the 2nd router everything is fine. I turn on my computer (which is plugged into port 2) and i went to network connections (windows vista x64, nvidia nforce networking controller) and changed the IPv4 address to automatic for both IP and DNS. It connects fine and my ip address changes to a 172.18.231.xxx form but when i try to connect to the internet, it wont let me. so i typed in 172.18.231.169 (1st router ip) to access the router and it worked. i pinged the router and it worked. Now my questions are....

1.) How do I access my 2nd router using internet explorer (firefox, etc.)?
2.) How do I get my internet to work again?
3.) What else should I do?
4.) Can you make me a step-by-step guide on how to do this all (if you want to)?
5.) THANKS! (not really a question, though)