Getting Started in Source Thread

I've been playing TF2 for a while and would like to mod it. I've poked around looking for guides on how to mod Source, and I haven't found anything that tells me what I need to know: what do I need to start modding, and how do I get started?

Specifically, I want to make a modified Medieval Mode, with a few functions not normally found in TF2. I want characters to be able to lock onto each other, for example. I also wants to program delays when changing direction and/or jumping, to give the characters some sense of momentum. Since I'm not familiar with modding Source, I wanted to use TF2 as a basis and start with minimal modifications.

Is this feasible? Where can I learn more?

EDIT: Well, I just found SourceMod and I think that's pretty much the answer I was looking for (at least initially). But if anyone has anything to add about SourceMod or alternatives, I'd be happy to hear it.

Edited by: SAAj

I'm realizing how stupidly complicated it is to make even simple modifications. Would working in GMod or something similarly basic work better than attempting to mod TF2? The system I want to create doesn't necessarily rely on TF2, it's just a good starting point. But if it's going to be this restrictive, I'd rather have more flexibility.