It's cool that you want to play JA2. Go play JA2. It has Bobby Ray's and Skyrider in it, unlike all other Jagged Alliance games. It also looks almost exactly like JA2.
I just bought JA2 on GoG and downloaded 1.13 mod. Going to play a real tactical game.
I got no idea what I am doing with this mod, I will not touch any of the default settings and how I do not get raped in my first run. I am not using AI mod, just base 1.13.
Depending on what version of 1.13 you installed, you might be in for a rough time with default settings.
Enemies in adjacent sectors coming in to reinforce during combat is a big one, you'll need a radio operator merc jamming communications to safely avoid it. As a bonus he can call in artillery strikes too.
Expect a massive Drassen counter attack, enemies using spotters to snipe you from across the map, any bullets flying close enough by your mercs have a chance of eating their AP in suppression, enemies climbing and flanking, female elites, etc.
It's also a good idea to drop your backpacks before serious fights.
Also if you see Mouse is recruitable it means you can have her use the new disguise system. Use a knife on corpses until you get a shirt and pants, then you can scout enemy buildings safely.