I've not really built all that much, mostly scenery and the basics of a entrance so not really done much building so far, but i know what you mean, the flickering of textures fighting to be on top, i've seen it in the youtube channels i follow.
The high vs low, thats pretty common with alpha stuff, the different quality grades of assets etc, specifically anything but high quality simply wont exist until its locked down and they'll produce the LODs and stuff to improve performance. Right now it might be considered done, but not final, so rather than spend time faffing a few times for everything, its more or less raw.
Paths... yeah, i knew they werent popular but yeah its quite horrible and inconsistent. I had my main entrance path down the middle of the park, did a pair of 90° paths. Then i saw i was able to add a path at the 45° angle which created like a webbed-food type path connecting to the existing paths, and it looked really nice for sending ppl different directions. Went to put it on the other side, it just didnt want to know, where right side had a few variations of what i liked, the left had nothing.
Deleting paths is horrible, making bridges is a real PITA as the pieces of path are so large it just doesnt work how you want it to. There might be tricks so you can do things exactly how you want without the back n forth, but its not user friendly.
Tomorrow i might try and take a look at some built parks and draw inspiration, cos i stopped playing when i realised what i was trying to do was poop and didnt know what to do, i dont want to just plop coasters in till ive got some basics in, so its feeling a bit boring and frustrating.
What i really hoped Frontier would do is have multiple skins for each ride, so a single ride could be styled for pirate, sci-fi, medieval, fantasy etc. Right now, the rides are themed and simply dont fit many park themes. So if you've started a sci-fi zone, you cant go sticking a whirly-rig (iirc) in there with its barrels & squids theme, but if they were rockets, the same ride now fits 2 settings. It just feels very restricted because they've given many of the flat rides a theme. Also, a lot of the rides just feel huge, so tall and out of place. I wish they were modular like earlier RCT titles where you added what height you wanted them to be.