I just checked the standings, and it seems you're right there. The Suns have just leapfrogged the Kings in the standings and are now 3 games ahead. My bad. Before this 7-4 stretch, the Kings were ahead.
In terms of NBA talent, the Suns certainly have more up top but only go 5 deep (Booker, Ayton, Oubre, Bridges and Rubio). On the Kings, the following players have NBA talent and would get playing time on the Suns over anyone outside that top 5: Fox, Bagley, Hield, Bogdanovic, Barnes, Bazemore, Ferrell, Dedmon (this bad season aside), Giles, Bjelica and Holmes. In other words, twice the depth.
Cap wise, the Suns have $91,769,395 in salaries committed for next season. Counting expiring deals, the are currently projected to be $31,441,270 over the cap heading into next season, with $55,671,875 in cap holds for expiring deals and an incomplete roster charge (a total of $24,230,605 for free agents and draft picks, if we renounce everybody who is expiring, with another $5,005,350 possible if he cut Kaminsky):
https://www.spotrac.com/nba/phoenix-suns/cap/2020/
Sacramento, on the other hand, has $105,317,658 in salaries committed for next season, but that includes $61,856,462 in cap holds for expiring deals. These numbers also grossly overestimate the contract Hield is going to get, estimating a cap number for him at $26,431,818 (not that it matters in terms of cap space for this coming offseason, since Sacramento has Bird rights for him):
https://www.spotrac.com/nba/sacramento-kings/cap/2020/
So, to summarize, I was wrong on the first and right on the second and third.
Sorry for being mistaken on the first.