The current raids for Shadowbringers are old enough that the weekly loot restriction was removed and a buff called the echo was added that buffs all the stats a lot, so you can farm all of the gear.
When the EW raids release there will be a weekly loot restriction from each of the 4 floors and there is no guarantee you will get that loot. If you don't get it you still can't roll again for the week.
You will have 10 slots to fill with gear, so in the best case scenario you loot 4 pieces and get 1 piece of tomestone gear on each of the first two weeks, but that's unlikely to happen and it wouldn't be likely to have desirable substats. After 4-8 weeks you can get 1 piece from each floor with books.
What use the gear has is a good question. You will be a lot stronger in the latest dungeon, open world content and all the current expansion's 8 player content such as alliance raids, trials and extreme trials, but it's not necessary to be this well geared for them. This item level is needed for ultimates, which are not always released, but will this time after a few months.
One of the problems with a free company doing raid content is that if it has 9 members trying to do a raid that requires 8 people, one person gets left out and this is actually a really common problem when a free company raids together. A free company may still help though, especially with casual content like deep dungeons and instanced areas like bozja.
