1) I think this is one of the best Rome mods I've seen. And I love the time period/setting, too. Is anyone else still playing this mod? I find it really challenging even on easiest level, and I have never yet won a campaign.

2) Factions - to me there is a clear and simple bipartite division into settled factions (Anglo-Saxons and Celts) and raiding factions (Danes and Norwegians). For the former, it's easier to develop your settlements and economy gradually over time and expand locally, whereas with the latter it's much harder to retain any settlements you take, and you're usually forced to do just hit and run actions because of the massive unrest penalties you get if you try to hold any settlements which you did not start with. I'm not sure which style I prefer or even find easier, as they both have their plusses and minuses. But I am finding it rather easier to keep my economy afloat as the Norwegians rather than as the Danes, and I'm not quite sure why this is. Perhaps because the latter have fewer starting settlements, and what they do have can be more easily attacked by their enemies. Also, their main enemies are arguably tougher than those the Norwegians typically face.
There are some excellent-looking guides here in this sub-forum and I hope one day to even be able to win a campaign!

3) Mercenary Jomsvikings - OMG these guys are tough! An Alba stack attacked me and it was nearly all peasants and merc rabble. I had spearmen, Vikings, archers, huskarls, berserkers, generals bodyguard, plus others. But they had one unit of Merc Jomsvikings. I killed off nearly all the other units, plus the enemy general, but the Joms just kept fighting. I threw everything I had against them - huskarls, berserkers, my general's unit - and they ripped through them like it was nothing. Kept killing, killing, and more killing. I could hardly kill any even with my toughest units. Basically, that one unit won that entire battle for Alba. I've never seen I think such a hard unit in Rome or any of its mods.

Cheers!