Best to check with Malaysian Diplomatic Missions for current situation. Passports must have 6 months validity. Safe to drink from the tap in towns. Hotels and restaurants provide boiled water. Bottled mineral water widely available.
Casual dress is the norm, light cotton clothing is recommended.
Items such as films, batteries, torchlights, raincoats, slippers, etc. are available in all towns. Indigenour handicrafts and textiles, potteries, antiques, etc. are good bargains. Sarawak is probably one of the safest places on earth, crime rate is low, there are few dangerous animals in the jungles, general health si good, there are no earthquakes, volcanoes or cyclones and there is political stability, racial harmony and tolerance, no terrorism and no internal strife.