I for one have never really used the staff of the lost sun, and I doubt I will really. As already said, unless someone is running guys out on their own, its almost useless. Stegadon warspear is the winner for the chief methinks
In the same unit? I don't think you could do that. The skinks are on 20mm bases while the Slann is on a 50mm base, which means he is 2.5 skinks across and won't rank up nicely. According to the 8th ed rulebook, if you have a character that doesn't fit in a unit nicely (like he would in the 25mm TG) then he will instead sit next to the unit. He will still count as part of the unit, but its a very vulnerable and exposed place to have the Slann.
If I try this, I would run the slann in a unit of TG and use all those skinks as a flanking unit. I tried out a build and I was able to get 4 skink chiefs and a skink priest in there with 3 kroxigors and about 50 skinks. I also had 2 units of skirmishing skinks as well to round out the core. I usually do not take saurus anyway. I also placed a skink chief bsb in there with the skavenpelt banner. I could also take a lightly built slann and Tehehuian to use his beasts lore and take life on the slann. But that would only give me a 2 in 6 chance of getting savage beasts with him.
not really. unit of skinks + chiefs (maybe krox) for the chiefs and a TG+Slann unit either behind it, or in its flank. there is no reason for the slann to get into combat when both spells have a 12" radius
But the Lizardmen book has its own rules for how different sized bases rank up and since army book overrule massive tome then the more liberal Lizardmen rules apply with bases rounding up to the next multiple of the smallest size if they aren't already a multiple.
i have a chief and have found they can be very accurate with a blowpipe, and having three shots generally means they get a good chance of hitting
regarding blowpipe: its still only 2 shots as per weapon profile, the number of A the chief has on its profile doesn't apply regarding different base sizes: page with the army rules. the problem is they only mention different base sizes that are multiples of the other ones; skrox : 20x20 - 40x40, slann 25x25 - 50x50. otherwise he will still be in the front rank. they say you should try to fit him in the middle, but if its too awkward, put him on teh side iirc