CTCSS & DCS codes/tones are like sticking your fingers in your ears except for anyone also on that specific code/tone. Everybody else without the tones will hear you, but you won't hear them. It's the opposite of privacy. Reference a big Jeep event, there are 22 channels, not 8, but if you wanted to be on the same channel and not hear everyone else, CTCSS/DCS codes are designed exactly for that. Not sure how well that would work on a super busy frequency in a small area though, sorry. I'd just use a different channel.
You can run 5/15/40/50w on simplex or a repeater. One is not related to the other. Mo powa (watts) = mo range. Mo buttons = mo features. For somebody who is only going to turn it on occasionally when they hit the trail and want it dead nuts simple, the Midland MXT275 is fine.