The left one is probably Sedum 'Burrito', a form of Sedum morganianum, the middle one is An Echeveria, possibly 'Perle von Nurnberg', the right one could be Crassula ovata - aka the money plant. The Echeveria and Crassula have suffered from being kept in low light levels- they are etiolated, and need to be kept in as much sun as you can muster, to attain their true form, but do it gradually so as not to scorch them! I grow these plants in a greenhouse in full sun, as they would do in habitat.
Oh yes, yoink, a windowsill is a MUST! South facing if possible - these plants need all the sun they can get! As for watering, well, succulents are adapted to survive dry conditions - they store water in their leaves and stems, so overwatering can easily lead to rot and ultimately death. The usual advice is to water once the pots have dried out, so in the summer that probably means once a week - if in doubt, don't! Winter is a little different, because if kept in a warm room they will still need to be watered, but less frequently, say once every 3 or 4 weeks. In my greenhouse which goes down to 5C in the winter, nothing is watered between October and March, as they stop growing and enter dormancy - but inside a house you'll have to continue, but carefully! If the Echeveria is 'Perle von Nurnberg' (and I suspect it is, many are sold through Wilkos, and DIY sheds) , this is a pic of mine which shows how it looks when grown in a greenhouse with full sun.