My dad was recruited by a local company back in 1993. Somewhere in 1996, he was given the privilege to apply for SPR. He was awarded on his first attempt and being the sponsor, my mum and i also attained our SPR status as his dependents. Back then i was 6 and had been here since then. In 1997, He purchased our first resale HDB flat and we moved to our new flat in 2005.
In 2002, my younger brother was born locally and was given a SPR status as well. Currently he is studying in a local secondary school. He had been in Singapore since birth, less some of the occasional overseas holiday trips. My parents have all intentions to let him serve his NS in Singapore, just like me. My mum had been on odd jobs and since my brother started schooling in 2009, she had stopped working to help him with his studies.
In 2007, my dad was given the opportunity to be deployed overseas for a long duration. Since then, he was given 3 family visit per year and each lasting for a duration of 2 weeks. For the past few renewal of e-REP applications (2011,2006,2001,1996) that we submitted, the approved duration had always been 5 years. Until the most recent application in Nov 15, the approved duration was only 1 year.
I had since converted to a SC by registration and at the verge of starting my own family here in Singapore. Looking through the forum, i realised that majority of the 1 year REP were awarded due to insufficient time spent in Singapore and I fear that maybe the case for my Dad as well.
I had the following questions in my mind, hope to gain some clarity from the members and the moderators.

1) What are some of the factors that ICA take in to considerations when they decide the approved duration for REP? By duration of stay in Singapore? If so, are there any specific period? Are income tax and CPF contribution determining factors as well?
2) My dad was told by his company that for the duration of his postings overseas, all salary would be paid to him in the currency of the country that he was posted to. On separate account, he is given local salary as a form of financial support for his family who remained in Singapore. The allowance that were given was at its bare minimum, i.e. less than 20k per annum. Based on income tax guideline, there would not be any income tax for income group less than 20k per annum. As such, my dad had not been contributing to income taxes since 2007. Could that be a possible reason for the reduction to 1 year of REP?
3) In my humble assumptions, REP and SPR are interlinked but two different entities. SPR are allowed to hold REP for re-entry into Singapore. However, losing REP does not necessary means that the SPR status will be losed as well. Yet again, it does spell danger for my dad's SPR status?
4) Given that my mum and my brother are both dependents to my dad, their SPR statuses would also be affect should my dad's SPR status be revoked? If so, how can i, in the capacity as a SC, apply any form of statuses/permits for my family continue to stay in Singapore and retain our way of life? My brother is currently into his 2nd year of secondary education and it would be extremely disruptive for him to continue his studies in another country.
Hope to hear from you guys soon.

Regards,
Concerned son.