Changing the pups is a good move and a worthwhile upgrade.
Tuners are worth changing if the existing ones don't do the job.
I can't abide those little closed back tuners that are on some of the Squier range. If your bass has those, then you will need to enlarge the holes through the head stock, if you want to fit standard ones.
I have swapped out the wiring and pots on the Squier projects that I've done, not so much because I expect an improvement in sound but more because I'm not keen on the flimsy wiring and little pots.
If you want to take the easy route, then a fellow bass chatter, Kiogon produces a superb little kit that you can drop straight in, with no soldering needed. Decent pots, input socket and good quality cable.
The Squier bridge, I think does the job as well as a Fender bridge, so probably only worth changing if you don't like the look or it's faulty.
Good luck with it and enjoy