My kids are 6, 4 1/2 & 2 1/2... I still help them clean-up their rooms (to keep them on track, move stuff around to sweep & make sure it get's done), but they do help with house work. I feel kids chores should be based on their ablities... my kids are required to clean up toys before they go to bed each night. My 6 yr old likes setting the table for dinner & puts her folded clothes away after I carry them upstairs. My 4 1/2 yr old sets the table sometimes & helps bring down dirty clothes from upstairs. My 2 1/2 yr old helps me get stuff out of the fridge when I'm cooking... onion, butter, milk (if it's not a full gal), ect. All of them like to help put laundry in the washing machine - which ever one helps get to push the beeping buttons & start the washer. They also like helping to put away the groceries & helping me garden... it does take me a little longer to do the task sometimes, but it is time I'm spending w/ them & it teaches them to be helpful & responsible. My kids aren't old enough to take out the trash, but my daughter will put in a new trash bag when I'm running the full bag out. They also help to bag up the recycle stuff & get it ready to go out.
We don't really have rewards for chores... we feel that we are a team & inorder for a team to run smoothly, we all have to help it along. We do take the kids to McD's now & then for a treat and sometimes let them pick out something at the store. We are a very low income family, so rewards are hard for us to afford - so a lot of our "rewards" are walks in the park, playing games with the kids, sitting down & building w/ Legos or pushing cars & trains around on the floor w/ them... my kids kinda understand if they help, it gives mom & dad more time to be with them - and in their eyes that is enough of a reward.
I wish you luck - start off with just a few small ones & work up from their... I know as a kid mine were - feeding the chickens, collecting eggs, watering the cows & chickens, getting my brother feed & off to school, taking down, washing/drying, folding & putting away the clothes, taking out the trash, tending to the garden (dad planted, we weeded, hoes & picked it - it was over an acre), racking grass clipping & giving them to the cows & chickens, racking leaves, in the summer making lunch for my mom & brothers - guess in a way I was a mom before I had kids... my chore list started when I was younger then your kids & by 10 is when I was making lunch for everyone & it continued till I was 17 and married... but then it just normal for me to be a caretaker & I started taking care of my hubby & oldest daughter (who doesn't live with us - really long story) instead of my mom & brother. Oh BTW, there was nothing wrong with my mom - she just didn't like doing anything, except loading the dishwasher, but my step-dad thought she was a great mom & wife because everything was always done when he got home - including his lunch packed for the next day... he learned after I married & moved out who was doing the work.
I do understand teaching kids responsiblities, but please let them be kids too. Don't go to the extream like my mom did with me.