To answer the questions:
This is a bit of a non-issue at the moment but does LA have to clear space when RV gets back?
Yes. They are also 23/23 on roster size. So if he's back before the trade deadline, they'll have to free up roster space, too. After the deadline, the 23/23 limit is lifted, but the cap is still something that would have to be freed up.
How much will need to be cleared?
It depends on when he comes back and how they maneuver players to maximize cap space. I suck at the legalities in this area specifically - others are much better at explaining the ballpark numbers and actions needed to be taken.
Spence is waiver free at this point but has earned a spot on the team and is big piece for that matter.
Spence, Byfield, and Laferriere are all waiver exempt. Most likely candidate to minimize movement would be Laferriere.
Also, RV and Roy are UFAs at the end of the year. Will LA be able to retain them?
With the cap going up, and Kopitar's cap hit going down, it's possible. But the following players are all RFAs and some will likely require raises:
Byfield
Kaliyev
Lizotte
Bjornfot
Moverare
Grundstrom
JAD
Lewis is the only other UFA, so he frees up very little. This also doesn't include players like Clarke, Turcotte, Fagemo, etc of any other players vying for a roster spot.
Does LA consider a Roy trade in favor of bringing up Clarke?
In my opinion, not at the trade deadline. Maybe they'll trade his rights at the draft, but I'd say it's most likely that Roy just walks.
Keep them for a run and let them walk in UFA?
With what the Kings invested, they're pretty much all in. They're not going to worry about recuping futures in a playoff run, and with how tight the cap is, they'd be seeking a player on a similar deal. So either they bring in another RD, which is pointless, or they try to address another position and hope that Clarke fits in.
Since the biggest question mark would be goaltending, I just don't see them distancing themselves from Talbot and Copley.
So, I think they'll take the lowest risk choices:
- send down Laferriere and/or JAD to free up cap space when Arvidsson gets healthy
- take their chances in the playoffs with Roy and Arvidsson
- try to negotiate contracts to keep them
- let the players walk if they can't come to an agreement.
Edit: incorrectly stated Kaliyev is waiver exempt. Fixed the list.