Env3 Receiving texts pop up while I'm texting & how to block mass group responses

[STRLTESTRBRTE]

I've had this phone before and recently just got it again just for calls and texts. I have to VERY big annoyances that I don't remember having before. 1. A friend of mine loves to send out group messages and unfortunately I get everyone and their grandma's replies. It's really annoying that my phone keeps blowing up. 2. Is everytime I'm in the middle of texting, I get the pop-up saying a I have a new text message from so & and so and I always have to decline reading or replying right then and there because I'm not finished texting the current person. Is there any way to turn off or disable these matters?