Can I bring a French worker in the US through my LLC?

The short answer to your query is Yes. Your company can file a nonimmigrant or immigrant petition for your French citizen to enter the US to work for your company. There are several requirements including the existence of a legitimate business reason for the hire; the qualification of the alien worker to do the job for which, s/he is being hired; the financial ability of your company to pay the foreign worker the regular salary that is offered for a US worker. Please consult with an experienced immigration attorney.

That could be possible depending on all sorts of factors. Most immigration lawyers like myself charge around $2500 to $10,000 depending on what type of visa is pursued.

You certainly can petition the immigration authorities for a work visa for this French national. The petition might be for an E visa, L visa, or H visa; to recommend the best option, your attorney would need to know much more about your business and about the particular worker when the information you provided. It is possible that your worker's credentials and the nature of his work for you in the U.S. might qualify him for an O or P visa. You might also consider filing a petition for an immigrant visa (so called "green card petition") for your worker; however, it is a long process, and most employers prefer to start it when the worker is already in the U.S. on one of the listed work visas. The processing times and the costs will vary depending on the visa you will end up petitioning for, but, to give you ballpark figures, E, L, O, and P visas can take from 1.5 to 4 months (unless you are willing to spend $1225 for premium processing and get the petition adjudicated within 15 days) and cost $325 (petition fee) (plus $750 or $1500 ACWIA fee for H-1 visa plus $500 FPD fee for H or L visa plus $2000 / $2250 P.L.111-230 fee for H1/L1 visas if your business is required to pay it). H-1B petition cannot be filed until April 1 and, if approved, it would allow your employee to begin working for you in the U.S. from October 1. Attorney fees in most cases range from $3500 to $8000, depending on the type of the visa requested and complexity of the circumstances.

Maybe a L or H-1B visa is possible.