1. Can we use paper dishes or cups on Pessach? What about coating or glue that could be in it?
When possible they should be bought with Pesach certification, when this is not possible they may be used. The coating and glue is not known to contain chametz in these products, and even if it did, it would likely be unedible.
2. If we have only one minyan that davens after zman tfila have we to daven in that minyan or without minyan at a time?
Tefilla at the zman is more important than tefilla btzibbur, so if they will miss the zman you should daven without minyan, and then join the minyan for chazara hashatz, kaddish, kriyas hatorah etc.
see Mishna Brura 46:32
Thank You and Pesach kasher ve-sameach!!!