I have heard the best things for wee clean up is.... dab up liquid with paper towel, sprinkle on bicarbonate of soda wait until it dries and then hoover/brush up.
I have been letting my daughter use a potty for the last few months though she isn't potty trained as she is only 5 months old(that will wait until she is 2/3 years old) but 95% of her wee/poo goes into a potty/toilet at the moment.
What about putting old sheets or terry squares on the floor and encourage your twins to play on them...that is what I'm going to do once my daughter starts crawling.
We have just started to use Bright Bot Training pants and I love them as you can tell at a glance if you have missed a wee but no puddles on the floor.
I am a big believer in making things as easy as possible for you and your child and overall it is a lot quicker to potty a child and clean up the odd miss, then it is to nappy full time...that said all the best with the additional work with twins.
Try catching the early morning wee first, usually the easiest to catch and then try sitting on the potty after meals/naps. Poos are usually quite easy to catch, as you can see when your child is going to go, my daughter farts loudly before every poo which helps me get her to the potty when needed.
Above all relax. The more worked up you are the most stressful the situation will be and the harder for your children to relax.
After all it is only sterile wee we are talking about not anything nasty. I started off thinking that using a potty would mean a house full of wee/poo stains but I have not had one wee/poo miss on the floor (yet).
Hope that helps and all the best.