How do I manage photos that I don't want on all devices?

I have an iPhone 5C - 16GB using IOS 8.0.2. (Apple care purchased for phone).

I purchased an iPad 2 mini (wifi/cellular) using IOS 8.3 - 128GB (only had it for three weeks).

If you're responding to this, assume I have virtually 0 knowledge with respect to most things Apple.

I purchased the iPad to move all personal photos/documents/music from my work laptop (Lenovo T540p). I don't have a home computer as my work laptop has functioned as both for many years. My first thought for photo transfer was to move photos to the iCloud and then access them from there. I want the photos to be permanently stored in full resolution on the iPad and have no desire to keep them in the iCloud as I have tons of photos. I don't want to pay for iCloud storage. I downloaded iCloud for my PC. So many prompts came up that in general, I just said 'yes' because I had no idea what most of the prompts meant.

After doing further research, I decided to buy an adapter for an SD card and simply move photos from my PC, onto the SD card, and then from the SD card to my iPad mini. For the most part, this worked except some photos (taken on the same day with the same camera) wouldn't transfer over for no apparent reason. No big deal. HOWEVER, shortly after I started this process, I got a notification on my phone that my storage was full (I've had the phone for over a year and never been close to using the memory). The photos I was transferring appeared to be syncing to my phone, thus filling up the storage quickly.

Because I know nothing where Apple products/iCloud/syncing are concerned, I was afraid to delete photos from my phone fearing it would permanently delete my photos from everything. I read what I can from help communities, but it always ends in an endless string of more and more links that only serve to frustrate me.

Assuming part of this mess came from having downloaded the iCloud for PC which I never ended up using anyway, I decided to 'uninstall' the iCloud files from my PC (probably an erroneous assumption). I attempted to do this, but am not certain that I have succeeded. Then I tried to work with various settings on my iPhone and iPad to achieve what I wanted to achieve. No luck and now I keep getting messages on the iPad that say "this device has not backed up in 3 three weeks" and if I try to go into my settings on my phone to access the iCloud, I get the following message "Verification Failed - there was an error connecting to iCloud".

All I want is:

NEED TO HAVE - FIRST PRIORITY: to be able to move photos (and eventually music/documents) from my PC to my iPad without those photos (music/documents) appearing on my iPhone.

NEED TO HAVE - 2nd PRIORITY: to ensure my iPhone is running regular backups to the iCloud to protect my contacts and any other data essential to my phone/apps.
NICE TO HAVE BUT NOT ESSENTIAL: to have photos that I take on my iPhone appear on my iPad

Are these things possible? Is this a case of me having to go into an Apple store with my PC/phone/iPad to get this mess sorted out? I want to feel the Apple love, but I'm just not feelin' in. :-(

Kate