Hi, I recently visited the USCIS office. I was having multiple dilemmas regarding whether to file for TPS or not, and finally decided NOT TO FILE. It would be best if I can give some info that may be applicable to your cases or partly. TPS has become a common dialogue these days. :D 

If TPS gets renewed, you will not be able to apply the 2nd time if you were not regestured the first time .

Thanks @itroll. I re-arranged my post not to create any confusion.

@aarKIpaar
"If TPS ends and you still have valid I-20 (ie. I-20 which Duration of validity is beyond Dec 21, 2016) you will be able to get back your F1 status provided that you have maintained it during TPS period."
Q. How do you maintain F1 status by working off-campus and more than 40 hours a week? Is taking full time credits enough to maintain F1 status? What are the requirements of F1 provided you already have TPS?

If you are eligible now, you can still apply new TPS during renewal period if you didnt apply now !!

If TPS overrides f1 status, then from that analogy TPS also overrides h1, B1, J1 or any other status. Is that right?

From my understanding TPS doesn't overrides anything, other than the OPT EAD card and its just because you just can't have two EADs at the same time.

As long as someone mention his/her status during TPS, he/she can come back to the previous status when TPS ends.

This is just an opinion not a legal advice.

@damauli_guy, if you dont apply now, you cannot file for the first time later too. Please check the dhs tps page and see if el salvador, haiti, nicaragua .... etc can apply for the first time? Only renewal is possible. Some contries may be an exception like sirya.

@mero_naam_ho, yes tps overrides every previous status. You cannot be on any dual status at a given time. If that is not the case, why do you need Advance parole to visit home when u have valid visa and i-20? why you need EAD if you only want to work on campus (F1 does not need ead to work oncampus)? When tps ends you are back on previous status, conditions apply.

@BioMed As far as I know there are somethings which are known to your DSO, and something not known. They know how much courses you had taken each sem, whether you maintained full time course requirements or not. How much you might have worked on campus. They will make decisions based on whether you enrolled full time or not when it comes validating your i-20. There are students who work more than 20 hr per week on f1 and still have valid i-20, you know that. Gas stations, convenient etc.

Now, to your question that can you legally work more than 20 hrs per week? Now read this, what if you worked for only an hour per week offcampus,, forget about 20 hrs, did you violate f1 conditions, since f1 is allowed only to work 20 hrs per week ONCAMPUS, only economic hardship category is allowed to work offcampus. So, i think the "20hr" rule is a just a mere satisfaction, since we are used to it. I guess you would be allowed to work more than 20 hrs, and you should take full time courses at the sametime. Talk to your DSO, and let us know what they say.

When you are almost ready to graduate, and you have only one class left. You take one class, and still maintain F1 status. I think is depends on school, if they let you maintain your F1 or not. Condition applied.

I am thinking of applying for TPS and I will also be traveling to Nepal for a month on August 6th 2015. Although I will be applying TPS before I go.
So I was wondering if it will affect my pending TPS application? If it does, are there any other ways that I can apply for TPS?

As far as I know, if you apply for TPS then you have to have advance parole (travel document) to leave US and come back.

TPS is a "hybrid" status , it does not affect the current status you are in , there is always + and - s , its part of life but having a back up here in USA is not bad and you wont have to regret after the December 2014, for that reason lots of F1 and with OPTs are applying for TPS , its a economic hard ship in the country for that reason it has been granted and predictions is that it will be renewed for some years at least few times for sure !!! so think properly and decide , the decision is definitely yours >>

@Tsering Namgyal. If you travel outside while your TPS application is pending, it will be considered abandoned, hence your application remains void. If you apply once you have completed your trip (within application deadline) still you will not be eligible since you do not meet the continuous physical presence criterion. The only way your TPS remains valid is to apply for Advance parole document and get it approved for the visit before you leave under any circumstances. If you are interested in TPS, i would suggest you not to leave US unless there's an emergency, still you must have your travel authorized.

Everything you wanted to know about TPS with relation to F1, H1 and OPT directly from a horse mouth:
https://www.youtube.com/watch?v=K6e0BtBe4AU