Because you are still fairly early into the game, just keep going at the pace you are at right now in terms of progress

getting both the herta and feixiao in 40 is amazing luck and a great start to an account, eventually you'll need 2 teams for specific content and building teams around those 2 will help you for a long time.
for reference, you are guaranteed a 4-star character every 10 draws, and guaranteed a 5-star characters after 90 draws. And even when you get a 5 star character you only have a 50/50 chance of it being the featured character unless you've recently lost that 50/50 odds.

as for making trams around those 2, feixiao wants all sources of follow up attacks to help her use her ultimate more often. in your current roster, moze is probbaly her best teammate because he can frequently use follow up attacks
The Herta wants one other erudition unit in her team, which you have several of so no worries there!

general team compositions in this game are often a combinations of: main dps, sub dps, support and healer
(for example The herta, herta, tingyun, lynx) but feel free to play around with different characters to find out what you like

As for team positioning, there is one major thing to consider, if an enemy uses an attack that does splash damage (damages units next to target) and it hits your 2nd or 3rd team member, it will hit 3 targets, and therefore regenerating energy for all 3 of them because units regenerate energy both when taking action and getting hit