If you are working with true males you cannot make feminized seeds.
If you don't really care and are trying to do this as a cash grab, potential buyers will see that and likely not be so interested, also it is apparent the seed market is cooling off imo, you may have missed the rush.
Yes you can use 6 males to pollinate individual branches but unless the female is huge you will be disappointed with how many seeds you end up with. This is not how breeders are doing it for seed production runs. Maybe some do this to create a small batch of seeds for testing before doing a seed production run but otherwise it is not going to be useful to someone trying to sell seeds.
Yes it does take time which is why most pollen chucker breeders will often use one male on several female, this nets the most seeds and crosses in return.
No that is not how cannabis filial generations work. To get a true F1 the male and female cannot be related up through their family trees. Most people now call any male to female breeding an F1. In any case, if you take two F1's (a male and female) and cross them, you have an F2. If you do what you describe once you self it to feminize it you have an S1.
I would suggest stop, put everything on pause and do some research. Breeding takes knowledge, time, patience, money, knowledge, space, patience, testing, luck, etc.