2006 dodge charger with a viper 5901

I used to be a professional installer for several years a while back, but Ive been out of the game for a while. I have a Viper 5901 alarm/remote start that I'm installing in my personal vehicle, a 2006 Dodge Charger R/T, that does not have a factory alarm. I also have the CHALL Xpresskit, and the CHTH2 wire harness for the bypass. I use to be a wizard with DEI products, but things seem to have changed a bit, and the installation manuals that came with these products definitely leaves some room for questioning. Here are my questions:

What is the difference between 1-way D2D and 2-way D2D? The installation guide that came with the CHALL seems to say that there's an entire harness from the CHALL that needs to be connected to the Viper brain ONLY in the case of 1-way D2D. I can't tell if I'll need this or not.

The guide for the 5901 says the jumpers on the side are usually left in the default horizontal position, and refers to the install guide for the xpresskit. The xpresskit install guide doesnt even mention these jumpers, so what gives?

Also, are there any additional tips anyone can give me before I go tearing my dash apart? DEI used to be a lot clearer with their documentation. I'm starting to wish I hadn't bought a Dodge. Thanks a million for any help you can give me.

Do u feel like losing a key?? If so do the 556u and be done with it. Those alarms are fairly easy besides all the relays...pretty much everything is behind the cluster. It's a little time consuming but its not bad.