Hello, welcome to SW and Minis
Firstly, your Healthy Extras are there to provide you with things we all need in our diet - fibre, calcium, protein etc. You are advised to have them. I didn't used to, but I've found that having them actually helps me. Especially if I use my HEb for high-fibre foods such as Ryvita and bran flakes. Fibre is great for helping get things moving, which aids weight loss.
Having a bit of cheese makes me feel like I'm being really indulgent, as other diets I've been on are very restrictive when it comes to cheese. I've never eaten this much cheese in my life! But calcium isn't just good for your bones - it also aids weight loss apparently. There has been research done and results have shown that women who have a calcium-rich diet on average lose more weight than those who eat the same kind of thing but without the calcium. I know you can't believe everything you hear when it comes to 'research' but this is one I really think works.
When it comes to syns, you need to find out what works best for you. Most people here, from experience, would advise that when you're starting out, you eat your full syn allowance. Otherwise, when you hit a bit of a blip or stall in your weight loss (which happens to lots of us, but not all) you wouldn't have anything to cut back on.
Also, there's such a thing as not eating enough, believe it or not. Having you syns ups your calorie intake slightly. If you eat too few calories, your body really does go into starvation mode - it clings on to whatever fat it's got, because it doesn't know where or when the next calories are coming from, so it stores them for use, in case it needs them..thus making it harder to shift!
I think the best thing when you first start is to stick to the plan absolutely by the letter...follow the book, do what you're told. You'll lose weight! Then, if you're finding things aren't working for you, that's when you can start tweaking things to suit you.
Good luck