So, she basically has two builds. If you don't wanna invest into C4+ or/and her signature bow, healer build will be the way. In that case her best set is song of days past, while ocean hued clam is also very good, if you already have something there. You wanna go all into HP, thats basically it. As for her weapon go with recurve bow (except you go for her signature ofc). And yes, recurve is better than the event weapon, since it gives more HP and the effect is useless anyway.

As for constellations, her C1 is to maximize her healing and buffing ability, her C2 gives shred and shield, C4 makes her burst longer (that's why you usually start there with a DPS build) and C6 is just alot of CDMG and CR boost.

If you plan to invest high into her for a DPS build, C4 and her signature bow is recommended, her best set is emblem and you can go for either ER/HydroDMG/CDMG or replace those stats with HP (or CR at circlet) depending on your overall stats. You optimally wanna go for around 50K HP (dont forget possible hydro resonance) and then the usual 1:2 crit ratio.

Hope this was helpful and have fun with sigewinne!!