Can I upgrade ram? apple says only 4 gb ram per slot

First, this is the Blog area not the store front. Here you will encounter knowledgeable volunteers answering questions based on their experience. Look at the score value under their name to get an idea of how that persons answers have been rated.

We need your systems info before we can answer your RAM question fully. On the most part Apple has updated many of the systems firmware to allow larger RAM configurations. Here's the Apple TN to check your firmware and how to upgrade it: EFI and SMC firmware updates for Intel-based Macs. Many systems now can support 16GB of RAM using two 8GB memory modules.

As to your HD question: A hybrid drive is much better than a straight HD drive as it offers a deep SSD based cache. So you gain the speed of the SSD but also get the size of a HD. I strongly recommend them. Seagate offers a nice unit. We have over 200 MacBook Pro systems in the field that have the Seagate SSHD units. I don't recommend using the dual HD setups any more given the issues they face.

As to your other question on larger SSD's: Surprising you can get a 2 TB SSD unit but it will cost you! (around $3,500 US). For now stick with HD's if you need space, I don't see the prices dropping for quite awhile.