You dont really specify if youre playing with mouse/keyboard or a controller. The advice to tell people youre new is good. If typing a message while going is a problem, you can get the message ready before the dungeon. Typing something like...
/p First timer here or maybe /p New player here
and then hitting enter once you finish loading into the dungeon works. If youre on controller instead, you can turn this into a macro that you can hit with one button at the start of the run. Practice will make all of the issues you mentioned easier. Another thing you should do(if you havent already) is run the training instances from The Smith. The physical location of the beginners hall is nearby to the first dungeon you ran(Sastasha - outside of Aleport in Western La Nosca), but you can also access these lessons from any smith npc(they can be found at the inn in each starting town, as well as outside the first 2 or 3 dungeons). Doing the practices helps most new people, and you get some decent starter gear too. I cant give advice about novice network, because the quality of it varies from server to server. But i can say if you have specific questions, theres usually someone here who knows the answer. Best of luck, and welcome to Eorzea!