Can I play music on my phone and use the watch to control the music such as play or pause etc. Likewise, can I do the same if headsets are connected to the phone?
Yes, you can.
Are telegram notifications displayed?
No, there is no telegram notification displayed on the watch.
can i acess facebook , twitter and watch some videos with this smartwatch?
No, you cannot to acess facebook , twitter and watch some videos with this smartwatch. K88H only supports remote notifications only.
is it possible to change the strap of the watch to a normal 22mm stainless steel strap from the watch store?
Yes, it is possible to change the straps.