While yoofs are a good candidate for a shoota, they are also a good candidate for being dirt-cheap bullet sponges. One thing to remember is that enemies have to shoot at the closest target and they can only avoid that target if there is an easier shot to take. So, it does not hurt to have some dirt cheap Yoofs on the roster whose prime purpose it to move ahead of the rest of your boys and make sure that the enemy has to pump bullets into these guys first. That is generally how I get my boss and some other guys into combat.
The Orks biggest strength in this game is the large numbers you can have in the kill team (which was always a huge deal in Necromunda). Take advantage of the large roster and cheap Yoofs and use a number of them in utterly expendable roles.
On the topic of the boss, I recommend that everyone arm their boss with a Kustom weapon - either a kustom shoota (2 sustained fire) or a kustom shoota/skorcha (flamers are amazing in this rule set). I also recommend arming the boss with a big choppa. The boss naturally has 3 attacks and that is plenty for the way the combat system works in this game. You get a pretty negligable bonus for arming the boss with 2 weapons, but you get a huge increase in combat effectiveness if you give the boss a kombi weapon and a big choppa.
In regards to combat, you pretty much have to run flat out while hugging all of the terrain you can get and making sure that there is generally at least one cheap Yoof that is both the closest and easiest target for the enemy so that you can get close enough.