We bought the darn things home on our last trip to Spain. Staying in 4 and 5 star hotels.
So having experienced the huge cost of getting rid of the tiny offenders we will be being particularly careful. We bought a hot bag that everything will go straight in on our return home (it wont be coming i the house until its been treated) and I will be washing things a on a hot wash as often as possible... probably a good reason to use cotton, nylon and polyester clothing and not your best expensive merino.
Keep bags off the floor, seal it up, don't drop dirty clothing on the floor..apparently they love nothing better.
However we slept in some really awful looking beds on the El Norte a couple of years back and had no problem at all.
I don't know about Permethrin and its effects on bed bugs, but its been well talked about on here. We used it on last years 5 month Te Araroa hike in NZ and did not have any ill effects.
The cost involved in eradicating them is substantial and stressful. I can advise you that you don't want them in your house.
Bites are usually in a straight (ish) line and come in groups..Breakfast, Lunch, Dinner. If you get bites you've possibly got them in your gear. A Hot tumble dryer is supposedly effective. But Id do a hot wash as well to be n the safe side. Be like the old Levis advert?