you can practice your straddle lever on the beam.
if you can hang from something at home, you can practice leg lifts. Practice the straight leg ones and practice a high tuck to your chest and then extend your legs out. a tree, a pole work as well.
you can also practice leg lifts while lying on your back or v-ups ( situp while lifting your legs with straight ) and n-up ( doing a v-up in a tuck position ).
it is also good to do straddled v-ups
in your backward roll, make sure your arms are in your ears. I do not teach a swing back for younger levels because very often they do not swing their arms all the way up which creates a shoulder angle and their ears not covered.
it is not merely extending your arms like a handstand but important to put the bicep next to the ear.
it is a good to work wall handstands and pushups at home to increase your upper body strength. I rarely reccomend kids to work pushups and focus on doing wall handstands because usually their handstands are poor ( they cannot hold one past kicking up to it ) and it works all the upper body pushing strength they need.
as for your kickover/pullover- it is merely a matter of pullup and leg strength. it also good to work holding the top of a pullup position at your chest and doing this also with your legs in an L or toes higher than the bar ( V ).
- focus on keeping your arms as bent as possible as you pull your hips over the bar. if they straighten out as you pull your legs around, it means you have to pull your hips a longer distance which is harder. you can also do this in tucked position to make it easier.
as for your bridge, do at least 3-5 bridges 2-3x a day. shoot for holding 10-20 seconds. do it with your feet slightly raised so you can focus on straightening out your knees in the bridge. no more than a foot or two feet higher than the ground. this like the straddle lever and handstand is just a matter of practice.
if your shoulders are inflexible, practice hanging from a bar, or these:
YouTube - Stick Shoulder Mobility Series and these stretches:
Hands on floor fingers back in Shoulder Stretches Category
Cat stretch in General Stretches Category
Wall walks are another good thing to work for your bridge and strength/
GymnasticBodies.com • View topic - Bridge Wall Walks Build Both Strength & Flexibility
YouTube - My attempts at Coach Sommer Back flexibility drills # 1-5 they are the last drill in the video
i have a competition on 14 of feb and i have only 2 weeks in gym 2 train (2 classes) i have a small beam at home and a trampoline (14 ft) im having trouble 
with my straddle lever -i just cant seem to get it , my leg lifts on high bar -only get half way up, my bckward roll to front support -awkward looking 
, my bridge i cant get up with my legs together, and my kick up around the bar is not consistant
