@BioMed
Even if you don't want EAD now, you have to apply for it, but chose NO on the question>> are your applying for EAD?
Just apply TPS for now, and maintain your status. If you are planning to apply for OPT, and get a EAD then you don't have to worry about TPS EAD. If you are STEM then you will get EAD for 27 months. Let's say you did not get your H1B, then you can apply for TSP EAD if TPS continue till that time, but how your are going to maintain your F-1 Status that time. After your OPT EAD expires, either you have to go back to college, or you become out of status.

Tips: The good thing to apply TPS EAD now is that you can work outside, and after you graduate you don't have to wait for 3-4 months to get your OPT EAD. You can start working on any company the day you graduate :)

>> Will working on TPS EAD create any issue when applying for H1B through employment?
>>>> Nop, it will not create any issue, but if you apply TPS EAD while you are in your OPT TPS, then your OPT TPS will get canceled.

>> On different note, can all Nepalese working on TPS EAD apply for H1B in future if their employer agrees to do so?
>>>> It depends on everyone's situation. I think people who are living here legally will not have any problem, but I am not 100% sure about people who are living illegally. I will come to this question when I am 100% sure :)

@chulbul
If you do not maintain your F1 status then by the time TPS ends you will be out of status. I don't think you can go back to student again.
I don't know what is the condition you have, but you should continue your study, and work full time on your TPS EAD.