How to rengar? (Questions about Runepage, Clear, Ganking, etc.)

So lately ive played ranked and im silver 1 right now. Is it only me or does ranked feel shi* now you get ranked after a game which sucks. But thats not what i wanna talk about right now. So ive tried maining jungle role and main rengar in the jungle, but each game i play i do like 0. We just lose i dont know if its me or my team tbh lately my stats have been crap if im gonna be honest. We played a game and we had a over fed vladimir but he got to greedy and he went in 1v5 while we had a urgot farm and us others just came back to base. He died and we threw the game.

So like my point is how can i improve in jungle especially with rengar as im trynna main him, ive understood his basics i think but i need more. This is my jungle clear: Red buff (sometimes i mbe invade blue depending if they start blue/red usually its succesfull, crugs, raptors,(sometimes crab), wolfs or blue depending on the situation, gromp and last crab if not already taken.

This is what i see pro players do or guides on yt. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------What runepage should i use?

Currently i use electrocute but i see people playing fleet footwork and im not sure what i should do. The question is what should i play dark harvest, electrocute or fleet footwork or is it depending on the situation if i could get some examples it would be great!

Sometimes i play rengar top with resolve im not sure if thats viable if i could get a answer on what i should be playing on top/jg (what runepages)

I know how to combo with rengar but there is a problem this is one of the biggest weaknesses i have playing rengar how do i gank? like if i gank mid i usually tell my midlane to bait the target close to a bush but in my games people like never do that and im not sure how to gank other lanes aswell.

What build should i use? --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Lastly i have one last question sometimes i go against champions that are a bit to hard for me and when i try to search up strategies to counter em i get "Get "target" close to a bush and you win trades) But that just never happens.