css or themes and skins..which you use in website designing and if you use css only what about validations

Question

hi, i find it more confusing and difficulty in adjusting div tages to adjust text, links, image etc..whenever
there is requirement to add or update css page , each time it is big headache for me to again adjust height and width pixels..
it is taking long time also.
In this scenario..i like to know from senior friends who already working on asp.net website development ..
1.do u use css in designing of webpages ...css or tables which is best method
2.if you use css how do you manage...
3.as we cannot apply css to all controls..so do use themes and skin concept for designing
4.and importantly, i like to know if you use css means you dont use asp.net controls.So, that means you write all
validation code in javascript only. In this scenario...i like to know,is it ok to write validations in javascript rather than
validation controls in asp.net. Is companies allow that kind of development.
5.if possible please give me the link of the website you design recently, so that i have an idea of where u used css .

thankyou very much

arun