it wont be cold in mid April.unless it's rainning,it will be cool,so u might need to bring a core-tex coat with u,mostly short sleeves is fine.if there's enough time,its alright to take a train but not a night shift,or u will not see the views on the way.if u comfort and efficiency is very important to u,then flight is highly recommended.btw,food there is very hot.hope u like hot,enjoy ur trip =)