Like soapbuddy said, there is really not much difference between distilled water and rose water, won't affect your cream any differently either way, other than rose water might lend a rosy scent to the cream and maybe give the cream more of a therapeutic benefit than distilled water would. If you want a (possible? not sure about this) therapeutic benefit, use the rosewater. If you don't, or want to go the simpler, cheaper way, use distilled water.
You were asking about companies that sell rose hip seed oil. I know Mountain Rose Herbs does, but I am sure there are other companies out there that do as well, so do a google search and I'm sure you can find some. There is also more information on MRH's page on rose hip seed oil, about why it is good for skincare recipes, what it's nature is, etc., so hopefully that will answer your questions about rose hip seed oil.
https://www.mountainroseherbs.com/produ ... il/profileMost all fats and oils blend well together, so whatever oils you choose to use should mix fine with each other. It is the oils and water that don't like to mix, as Irena explained.
Apricot kernel oil and sweet almond oil are very, very similar, so you can use them interchangeably in your cream recipe. I know that these two oils are often used for creams, lotions, etc. because they soak into the skin really well and quickly. I'm not familiar with avocado oil or jojoba oil, but I'm pretty sure avocado oil is also very similar to apricot kernel and sweet almond. The more you use different oils, the more you will become familiar with all their different properties and develop your own favorites. Some of the oils can be very similar at first glance, but there must be little differences because people have their favorites anyway. Like you said, you don't want to buy a bunch of carrier oils right now and become overwhelmed, so just stick with the one you have for your first try at a cream. If your recipe calls for apricot kernel, but you have sweet almond on hand, it's fine to just use the sweet almond if you want. By all means, experiment with apricot kernel and avocado oil later, but no need to overwhelm yourself on your first try.
As for fragrance oils and essential oils, since you make candles, you may be thinking that you can't use candle fragrance oils in skincare products. And you would be correct! That could be harmful to the skin. However, there are hundreds and hundreds of fragrance oils formulated for soap, lotions, bath bombes, creams, etc. (Bramble Berry has a huge selection!) So if you like FOs and are familiar with them, use them to scent your cream. They are easy. Just make sure you get a skin-safe one.
However, that's not to discourage you from using essential oils if you want to, because you are correct when you say aren't essential oils better for your skin. Essential oils have therapeutic properties, while fragrance oils do not. There is a smaller selection of essential oils, but there are many that smell wonderful. Tea tree oil is one of the essential oils that has a controversial scent - it's very funky and musky and a lot of people, understandably, don't like it. But don't let that give you a bad impression of EOs; you can get some very heavenly smelling ones! Some that smell good on their own are lavender, orange, rosemary, lemon and peppermint.
It is your preference whether you want to use EOs or FOs, but know that you can use either.
Hope that helps!