الجواب وبالله التوفيق

As per the options described in your question, the best option is where you do not have to pay anything. There is gunjaish(provision) for (permissibility of) the other options mentioned as well. However, the options where you have to pay the share, if you get medical treatment then it will be impermissible to accept cash reimbursement for such treatments. Instead, in return of the share you have paid, the correct way is for the employer to manage the payment for your treatment.

واللہ اعلم بالصواب