You don't need to perform any activities "under" the LLC in question to make them valid. An LLC is a pass through entity that simply acts as a shield for your personal assets. Conducting business in the name of the LLC will not give you any more or less authority to write-off certain expenses and take certain deductions.
To answer your questions:
1) Yes but see my statement above.
2) It is tough to say whether you can offset your commission income with prior passive losses as it depends on whether or not you materially participated in the rental activities of your LLC.
The first level of participation is simply "passive" participation. If you and your husband do not materially participate in the LLC, then you are not active participants and the carried forward passive losses can only off-set passive income.
The second level of participation is "active" participation. If you and your husband were active participants, then you receive a special allowance up to $25,000 in which you can off-set passive losses against your ordinary income. You are an active participant in a rental real estate activity if you and/or your spouse owned at least 10% of the rental property and you made management decisions or arranged for others to provide services. "Management Decisions" consist of approving of new tenants, deciding on lease terms, approving expenditures, hiring contractors, etc.
The real question is whether or not your Modified Adjusted Gross Income (MAGI), which is reported on your Form 1040, disqualifies you for the special allowance. If married filing jointly, you may use the full $25,000 allowance if your MAGI is $100k or less, meaning if you have a $25,000 rental loss which you actively participated in, you can use the entire loss to offset your ordinary income. The allowance begins to phase out once your MAGI goes over $100k and is completely eliminated once your MAGI hits $150k.
If you were not an active participant in the activity in prior years, but this year the activity becomes active because you materially participate, then suspended passive losses can be used to offset income from the new active activity, but it must be the same activity as when it was a passive activity. And again, if your MAGI is above $150k, you won't be able to deduct the losses anyway.
The third level of participation is being classified as a real estate professional. If you are classified as a real estate professional, all real estate losses can be used to off-set you and your husband's ordinary income (assuming you file jointly). To qualify, 51% of the personal services you performed in all trades or businesses during the tax year must be performed in real property trades or businesses in which you materially participated AND you performed more than 750 hours of services during the tax year in real property trades or business in which you materially participated.
However, if you are working in the real estate field (i.e. as a broker) and working for someone else (i.e. you are an employee), you do not get to count these hours or services toward the two criteria stated above unless you own at least 5% equity of the business you work for.
So can you offset your prior year passive loss of $10k against your agent commission of $10k? Yes if you and/or your husband are an active participant in the rental real estate activity and your MAGI is under $150k so that you can utilize some of the $25k allowance. And yes if you can be classified as a real estate professional.
3) This can get dangerous. If you claim the business owns your car and you expense everything under the business name, you had better keep flawless records that show the car was used for its intended business purpose. Should you be audited, the IRS may disallow your business expenses and you will be stuck footing a large bill.