Is it permissible to give durood saying assalamu alaika yaa rasulullah like some of the arab shaykhs do?
Which Arab Sheikhs? Also masaail are taken from the Ulama and Muftees. However, the matter depends on niyyah. If the intention is that Rasulullah sallalahu alayhi wa sallam is present here and everywhere, then saying it is wrong as this is the attribute of Allah. However if the intention is that the angels are conveying my salams with these words then it is OK.
While in Madina at the Rawdah, one should say “Ya Rasulullah”