If you have visited the Warframe website, you may have noticed on the PS4 tab, the offer for a free starter pack, the link below. I tried the link and received a message in the PlayStation Store I was not eligible for the promotion, probably because I already used it in November. Try it anyway, your mileage may vary.
The IGN gaming website posted an article about a PlayStation OS update coming soon, with new enhancements. Follow the link below to read the article, update will be arriving soon, no set date yet.