1) It is not permissible to shave the beard based on obligatory precaution, thus you can follow the fatwa of the next most knowledgeable marj’a
2) This is definitely a difficult situation, however, you must find any way you can to pray on time if your employer is not giving you the chance to do so or you cannot find another job. Even if this means performing wudhu at work (in the restroom) and praying at your desk (for example) – then you can repeat it later if you could not perform it satisfactorily. Maghrib and Isha prayers can be prayed until fajr time of there is a really difficulty in doing them before the middle of the night. May Allah make it easy for you.
3) Khums will be 20% of any savings you have accrued at the end of the year from your salary.