I'm answering these with a pretty limited experience, others here are far better suited than me, but putting that aside.
1. Modding xcom is a pain in the ass, just the tools are a 100gb download (for wotc), and for vanilla is another 60gb (not sure on this one), so if you want a mod to both version you have to make them work on 2 diff tools, and with 2 diff ways of doing, maps are diff, textures are in diff place... it's a pain, doable but a pain nonetheless.
2. Animations are another major block, it can be done but you need to know some diff 3D techniques, like rigging and modeling. On top of that you need to import the skeletons and make them work with your model, with much care since a single bone can make anims bonkers. The entire process is not well documented and while some modders got success on that regard no sex anims were done so far.
So in summary, modding xcom is a bit complex, more complex than skyrim for example, it IS doable and anyone can learn (I did, so you can do it too), is just needs patience and time.