Hi lu lu. Would suggest you try Tepe brushes. They come in a number of sizes and you can use them to clean between brackets and also between your teeth. Not as good as flossing, but the closest you'll probably get with linguals on. Whenever I see my hygienst or dentist, they tell me I'm doing a great job and using the rights things to clean, so they obviously work.
Absolutely no regrets, taking the plunge to get braces is one of the best things I ever did. I had a bit of a lisp at first, but nothing major - most of the speech problems I experienced were with my lowers. I think it's much easier to adjust if you only have the linguals on one arch, so you'll probably be just fine.
I have no problems flossing at all. I have STb Light linguals which are positioned near the gum so the floss seems to glide into hard to reach areas no problem. One thing I couldn't live without and that's my SPAMTRONIC SPAMSONIC SPAMONAIDE SPAMSTER SPAM SPAMINATOR water pick, really helps blast away any food etc before I start the cleaning routine.
Love my linguals ! Speech problems on and off - had lingulas for 14 months. On elastics now for my last few months of treatment so hopefully the end is in sight.