My name is XXXXX XXXXX I'd be happy to answer your questions today. I'm sorry to hear about your situation.
1. It's still half his. He can't forfeit his half of the community property unless he specifically says that he doesn't want it any more. However, the storage fees are a community debt, and the judge can order him to pay you half the fees from his share of the community property.
2. You can ask the judge to order him to pay all of the fees prior to the date that he decided that he didn't want the items anymore. If you don't want them, either, and you can't sell them for enough to cover his half of the storage fees, you can still ask the judge to award half of the community property to your husband - I'm not sure what types of items you're talking about, so it may or may not benefit him to just give everything to you.
3. The debt is a community debt, because the unit is being used to pay for community property, and was initially being used to pay for his separate property. You could just as easily say that you only put your separate property into the unit because you needed to rent it to hold the community property. The judge isn't going want to spend a lot of time listening to that. If you tell him what's in the unit, he should just divide the costs unless you're talking about a large unit, or which 90% is your personal items.
If you're talking about filing a motion for costs using FL-301, since it doesn't fit any of the other options, that's an "other" motion. However, FL-300 has replaced both 301 and 310. That's why you're not able to find the 310. Here is the new form, with the instructions:
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