first HU match; strategy questions

A few days ago there were no good 6-max tables going so I decided to be a fish and randomly sit down at some reg's HU table (@50NL). We ended up playing about 1k hands, and I discovered that HU is super fun and great for finding weaknesses in your game, so I'm definitely going to play some more, even though I know playing HU at these stakes is probably -EV (as it turned out I got lucky in a few deepstacked nuts vs second nuts type situations and won a few BI's, so I'm a lifetime HU winner for now :P).

I have a whole bunch of questions about adjusting to your heads-up opponent and also a few hands to post, but I'll just start with a couple.

1) since I had no HU experience, I decided to keep things simple for myself by never 4-betting in position. I opened 80% of buttons to 3x, he 3-bet to 10x 20% of the time (linearly, i.e. his top 20% of hands), and I folded 65% and called 35%. First question is: how much am I giving up by not playing the 4-bet game? Is this an EV disaster or a reasonably sound way to play against someone not making big mistakes in the 3/4/5-bet game? Okay, so going to the flop my range is now wider than his but still contains nut hands... this gives him only very weak initiative, right? So is it fine to fold to only about 30% of his c-bets in this spot, and float/bluff-raise quite liberally (depending on board texture, of course), or should I be folding more?

2) OOP I was 3-betting about 25%, polarized and bluff-heavy (he was folding to 3-bets too much). In the pots where I flatted his button raise, he was c-betting about 60%. Virtually every time he didn't c-bet I bet the turn and he folded, so I guess his c-bets were linear as well. This means I should usually be check-folding or check-raising, and rarely check-calling the flop, am I right?

i think you're probably giving up some value by never 4 betting since your villain probably would adjust if he's a reg. You probably wouldve made some successful 4bet steals if you'd done it a few times. Top 20% of hands is a pretty wide range so you must've had the best of it at least a few times... most aces mid to high pairs?

I'm about as knowledgeable re HU as you though..

Looks pretty good sofar and sounds as if you were making the correct adjustments vs this guy for the most part. How much was he folding to 3-bets. If I have an opponent who's folding shiotloads you obv wanna be very bluff heavy with some strong hands to balance, but obv being polarized. You can even flat AA KK QQ etc sometimes if he folds shitloads to 3-bets and you have a somewhat aggressvie image for c/r flops etc. c/r overpairs HU canbe super profitable vs guys who hate to fold to c/rs.

if he is literally 3betting the top 20% of hands i'd imagine you are losing a shit-ton of value by never 4-betting. obviously what he does with that range to a 4b would dictate whether you are inclined to 4b bluff him (if he folds too much) or 4b wider for value (if he calls or 5b ships too much)

ps i don't play HU tables. i could be wrong.