The liturgical renewal isnt something im familiar with so I’m not sure how much help i can be. Dress can vary. Most guys wear button up shirts with nice pants. That being said, I’ve gone plenty of times in jeans and a zip up sweater and no one has ever made me feel bad for it. As far as i know the synods are more just the rules that they follow. The biggest difference between wels and ecla that i know of is that women can become pastors in ecla.
The service is straightforward. There’s some hymns, lessons and a gospel reading with the sermon.
If they are providing communion that service you wont be able to take part since you havent been confirmed.
Other than that its just church. Like any religion, you find good pastor’s and bad. I know a lot of people say Lutherans are strict, but mainly Lutherans believe Christ came and died for your sins.
Wish i could help more, try it out see if you like it. :)