Does onlinelabels.com offer empty cores for sale? If not, do you know where I can buy them? Thanks

I apologize but we do not offer empty cores or have a recommendation where to obtain these. If additional assistance is needed, please feel free to contact Customer Support at 888-575-2235.

Do the white gloss labels have the black marks on the back? As in the black lines

No, our rolls do not include black markings. Instead there is a 0.125" space between labels for Gap sensing.

What printer would I need to buy these and print in full color?

The inkjet roll labels we offer have been tested with Primera brand printers. The RL2799GW is compatible with the Primera® LX400 and LX500 models. We do offer the LX500 model if you'd like to purchase the printer: https://www.onlinelabels.com/printers

could i get some samples of the 3 x 2 matte labels i have a tm-c3500 printer will they work on that

You are welcome to visit the link below to request free samples of our inkjet roll materials for testing with your printer model. However, Epson's TM-C3500 requires rolls with a 4" outer diameter so the RL2799JW would not be recommended for your printer since it has a 5" outer diameter. https://www.onlinelabels.com/samples

Is this stock compatible with an LX-2000 printer? Other sizes of this same stock states it is but this size does not. Please advise. Thanks.

The RL2799XW has a 2" core so it would be recommended for Primera LX400 or LX500. You can see the compatible printers listed on the product page on the left side below the product image and Product Specs. I have included a link below for our 3" x 2" label, 3" core, for use with a Primera LX2000. https://www.onlinelabels.com/products/rl2800xw