First, let me say - I am far from an expert and I usually hesitate to answer these types of questions and wait for the experts with many more years of experience then me to give their excellent answers so I apologize if I screw anything up in trying to answer you.
1) The table on my saw feels as though it's not letting the wood slide nicely. Is there a solution ?
Many people "wax" their table tops to allow things to slide across more smoothly. I believe many use Johnson Paste Wax to do that. It also helps to protect the table.
2) I bought some Danish Oil last week and put it into a container with a flat bottom, as I've seen on the Internet, so that I could just 'dip' my finished pieces. However, when I opened it tonight it has a thick, almost green layer on the surface, like you get when you don't close a paint tin and the oil underneath is quite congealed. ??? The container isn't 'airtight' is this the reason ?
I would suspect that indeed the problem is being caused by it not being an air tight container.
3) If I have a pattern with lots of cuts, I have to stand up, loosen the knob at the back of my saw, loosen the front tensioner and then undo the clamp to release the blade. Then I have to do it all again in reverse before I can cut anything. Sometimes I feel like the proverbial yo-yo and I find it very tiring... Is there another way of changing blades ?
I have never used a saw of the brand yours is so I have no real answers on this for you. On my Excalibur, my Seyco and the Dewalt I started with, they have that tension knob in the back of the saw like yours does but you do not have to release the tension knob in the back of the saw. You only have to release the tension flip at the front and then release the blade at the top or bottom. Since you indicate that yours has a front tensioner are you sure you need to loosen both the knob in the back and the front tensioner switch? Now that said, I am not a very patient person, and having had a couple of cervical fusions done, I struggle a bit with trying to "see" to fit the blades in those tiny holes. As a result,, I am not a big fan of all those little holes and most of my projects are of different types of things then those detailed scrolled pictures with what seems like hundreds if not thousands of holes for those reasons!
Melanie