Managing fleets, well THAT is the hardest thing, make 2 lines (far apart, about 5 ship lengths and just run side by side through the enemy, one line to the right and one line to the left, yeah thats how battles were fought in those days. So you can even pat yourself on the back and say you are as good as any other admiral ;p Im not kidding, thats the most effective tactics, ships in coherent 2 lined ship broadsides are an MASSIVE deathzone in between their lines, if the enemy has 2 lines as well, rinse and repeat till everyone is dead. If you start to loose though you might want to micromanage ,p You can pause and give orders and even go to slomo...
Artillery is bugged atm, the best way is to put em in front of your LINE troops and set em to shrapnel, every enemy stupid enough to attack you from that direction will be mince meat. The problem is, the AI is not that stupid ;p Not always anyway.
An alternative is to make a really extended formation with line troops in front and your artillery a way back and a 2nd line troop "line" behind the artillery, when your first line breaks let loose the cannons ;p Before the front lines break fire at the enemy with normal cannons or explosives (depending on your research). Try to pince the enemy and don't even bother trying to move a 12 inch cannon around, they are deadly slow to setup ,p Though a single cannon can turn the tide, 1 shrapnel shot can kill a third of a line easily
To your other questions
- Early on its either firing or bayonets... so yeah, once your first generation troops run into melee they can NO longer use their guns. Research fixes that, and gives you the ultimate weapon, rank fire. Research that with priority, Rank fire is ABSOLUTE vital in this periods engagements. It means all 3 of your lines can fire in turn, and after that salvo usually not much will be alive of whatever wanted to rush you in melee ,p
- Line troops are best engaged with line troops, 2 on one, so try to pinch them in at the sides to get a \______/ kind of formation, with the enemy in between. Thats the standard tactic, but your flank guys are very easy pickings for attacks from behind by cav.. so protect them with your own cav
Do not try to attack line troops with cav frontal, that is 100% death chance ,p Always from behind, and NEVER in front of another line troop.
Hope that helps
Oh, if you want to maintain small group formations press G (for group) you can group smaller sections of your army and they will maintain the form you have given them BEFORE pressing G.
I agree between, the tutorials are completely pointless and tell you NOTHING important about the battle system, if you do your big naval battles like in the tutorial, you will loose guaranteed. The ai is better at micromanaging a huge fleet in battle than you are, so maintain 2 lines and behold the glory of the era