Question about equipment and positions

I am a tight end/cornerback/defensive end for my highschool junior varsity team and was wondering if I should wear turf cleats on regular football grass? Would it improve foot performance or worsen it? I do not like high top cleats they seem to make me run slower i think im gonna look at some low top cleats if turf cleats arent what i need... Please give all suggestions

Also the past year, i had a hard time hitting, to where i could get them to the ground but the coaches never really taught form tackling for long so I would just stop and break down and wait for them to come to me and usually just explode into them on contact...But that was last year when i played mainly defensive end and this year im stepping up to cornerback and need to learn to open field tackle correctly and need some good suggestions

thanks