1 The learned lover lost no time nor tide,
tide > opportunity
2 That least advantage might to him afford,
least > [the least]
3 Yet bore so fair a sail that none espied 4 His secret drift, till he her laid aboard.
drift > plot, scheme; and metaphorically: motion (an especially pleasing pun) laid aboard > (To "lay aboard" a ship is to run alongside or into her, with the intention of boarding. Spenser also uses "abord", "aboord" (cf. Hubberd 324, RR 185) to mean "adrift" or "astray")
5 Whenso in open place and common board
Whenso > Whenever common > [at the common] board > table
6 He fortuned her to meet, with common speech
common > ordinary; public