my oldest two are 19mo. apart when they were little they fought a lot till the younger one got old enough to play without destroying his sisters buildings and such then they got along great and now they are best friends it helps a lot!
hhhmmm... as far as activities...
Crafts are great if your child is in to them (my oldest loves to create and is like a mini inventor)playdough, crayons, child safe scissors, all help build a childs fine motor skills early which will make it easyer for her to trace and print letters eventually
anything they can build with is fantastic mega blocks, wooden blocks exe.
we LOVE our magnadoodle it has lasted 3 1/2years and is used almost daily exspecialy in the car its mess free drawing they can do anywhere my daughter has been learning to spell on it lately
reading of course is always great if it keeps their attention and they like it!
keep them active walks parks.. or just running around the living room to music and dancing
DONT buy a ton of electronic light up flashy baby toys my kids NEVER touch them not even the baby plays with them (well except this one she plays with Sing and discover piano plays music and my 8mo. old loves it)they all just take up space
also make sure they are involved in things with other children outside the home so they do hopefully learn how to relate to others its better to learn that skill early then late!
