I'm thinking about trying out some of those mods, but I need to get better with efficiency. I can get places, mostly. It just takes a really, REALLY long time because I'm not brute force unprecise about it, and I think if I had to juggle life support and supplies on top of that, I'd do pretty poorly.

With regards to stable liftoffs, depending on the shape and length of your craft, fins can be helpful to keep you pointing in the right direction, as can holding off on turns until higher (as you already discovered.) I like to turn on SAS first, then launch straight up, nudge my craft only slightly to the east when I hit around 50-100 m/s, but then don't touch anything until I get to about 10k meters up. That when I start gradually turning east to build up my lateral velocity (which, I didn't realize at first, is essential to achieving orbit.) There's a lot of weird trade-offs between engine power, length of the craft, stability of joints. I sometimes have to add lots of struts just to keep the craft from flexing and pulling itself off course into a spin just from wobbling like that.