I love my Aviva! The strips are definitely the expensive part of testing. I often bought mine on Ebay for half the price they cost in the store for the accucheck. It's a popular meter so people are always selling the strips.
I would not use your syringe to poke, that seems a little dangerous (safety-wise) and a waste of a syringe when lancet are so much cheaper. If you can make it back out to walmart or a drug store, lancets are the way to go. They are cheap, and much safer. I started with a 26g for Bandit because the 29-31 just wouldn't give me a big enough drop of blood.
Check your Aviva box, though! Most glucose meters come with a lancet device and a few lancets, so you could try those until you make it back out.
To convert to mg/dl you multiply your number by 18. We use mg/dl on the board, so Leo is about 475. I think 1.5u is a much better starting point, especially if you're not going to feed the dry food. Many cats drop 100 points or more just from eliminating the dry food. However, if it were me I'd start at 1u. Most cats do not need more than 1u, and you don't want to skip over the right dose. Too high a dose of insulin often looks the same as too low a dose, because glucose is constantly being dumped in the blood to compensate for the low blood sugar.
In my opinion, you should not give him the dry food at all. If he's a grazer, you can leave wet food out for up to 12 hours, longer if you freeze it or add some water. The reason why I say this is because the dry food is going to keep his BG high despite the insulin. Then you're going to have him on higher, more dangerous doses to try and regulate him. When you do finally try to eliminate the dry food, you'll have to start completely over from the beginning to adjust his dose (because he's going to need a higher dose than he should be on because of the carbs, and taking away the dry on insulin can send him hypo). He is never going to go into remission if he's eating dry food. Some cats go into remission in just a few days or weeks of the wet diet/insulin combination. The more quickly you can get him regulated, the better your chances are of remission.