The Fender Squire guitars are quite good guitars for their price point, and you're still likely to be looking to upgrade in 3 - 5 years. Not related to your question, but I recommend having a gear fund that you put some small amount of money in every month or week so when you start to feel like you've outgrown what you have, you have some money saved up.
Back to your question, I would say don't get too worried about getting the exact right guitar at this point. You're still learning, and as I wrote, you'll want a replacement or additional guitar later on.
If you get one with a tremolo instead of hard tail, you can always open the back with a screwdriver and lock down the tremolo and make it into a hard tail (effectively). You can't make a hard tail into a tremolo as easily. My very first guitar had a cheap tremolo, and using it caused all kinds of tuning problems, but I'm glad I had it. I had fun messing with the tremolo, and I learned all about the tuning problems with a tremolo, and I learned how to lock down a strat tremolo to make it a hard tail.
Regarding the pickups, it's really a matter of taste. If you are learning metal songs or harder rock songs, then having the HSS will help you get closer to the sounds of those songs. On the other hand, if you you're more about blues, pop, funk, and other genres, the SSS might be more true to what you want. I personally feel like an HSS is taking two great things (a humbucking pickup and a strat) and making them both worse by forcing them together. With an SSS, you have a strat. With an HSS, you don't exactly have a strat, and you also won't really get the humbucking sounds that you hear in popular songs that have those sounds. But it's really a matter of taste. I doubt you'll regret it later either way. If you're feeling the HSS, go with it.
One thing to know about the HSS wiring (in my experience) is that the humbucker has higher output, so switching to the H pickup will cause a volume bump up and switching to an S pickup from the H will cause a bump down. If you have everything dialed in precisely, that can be a bit annoying.