dumb and simple questions from a noob

Neither dumb nor simple....

You can build an incredible system from 3K, if you do your research and are willing to buy used. Take advantage of https://www.safeandsoundhq.com/ and Amazon and Crutchfield’s 30-60 day trials. You best value would be around 1K for an integrated amp and $1500 for speakers which leaves 500 for the source.

Just figure out your priorities, what type of music, how much detail, bass, clarity, imaging, brightness, neutral sound you desire to accomplish and that would determine your speakers which would then narrow down you amp choices.

PS: most members here can’t suggest anything for you for 3K, they spend that much on a speaker cable upgrade 🤣 - my rig cost about 3.5K too

As far as #1 goes I have 2 surround systems.

Cables through the floor in one. Tiny rears hanging from a drop ceiling with homemades in the front on the Severance (basement) floor.

Also could research the many rca to  wireless/bluetooth  transmit/receivers for surrounds, wides, height etc. Get a nice pair of speakers that sound good to you for 2ch stereo listening.  They will then be fine for fronts for the HT.  Look at an onkyo or denon for the receiver.  Good midfi and not break the bank.  I did all klipsch 11.1 for HT I’ve had for years that was, all in, probably more than $3k, but not by much.  
I built an entirely separate system for stereo though.

Here’s a complete system that’s more than adequate for your room and includes everything (except cables) for $2500.  IME for HT you need a really good center speaker and subwoofer, and this nails them both along with a great supporting cast including wireless surround speakers so no messing with long cables.  This will blow you away, and you’ll have $500 left over for cables although you really don’t need to spend near that much (lemme know if you want recommendations there).  Hope this helps, and best of luck.

https://www.svsound.com/products/prime-bookshelf

https://www.svsound.com/products/prime-center
 

https://www.svsound.com/products/sb-2000
 

https://www.accessories4less.com/make-a-store/item/yamrxa2a-rb/yamaha-rx-a2a-7.2-ch-x-100-watts-a/v-receiver/1.html

https://audioengine.com/shop/factory-refurbished/a2-wireless-speaker-system-refurbished/

https://www.svsound.com/products/soundpath-tri-band-wireless-audio-adapter

https://www.monoprice.com/product?p_id=31263

You can setup a really nice 5.1 system without having to run cables to the rear speakers from your receiver. Check out THIS LINK.

If you want to get a great set of speakers see JBL. You could get 5 matching 580 towers for around $1500 and the matching 550P sub for $189.

As for a receiver I like the new Onkyo’s with Dirac room correction and my second choice would be a Marantz at a discount at accessories4less.com. Anthem is very good but might be above your budget.

As for a source Sony makes great blueray players.