score:49
The answers to 1, 2 are very simple.
The Soviet Union presented itself as a "communist paradise." That is, a country where life was better than in capitalist countries. This was the main justification for communist power and social order. People traveling abroad could immediately see that this was not the case. When this had become evident to a sufficient number of people, the communist regime collapsed.
Travel restrictions were severe, to all countries. But it was somewhat easier to travel to socialist countries. The reasons for restricting travel to socialist countries were that they were somewhat different, and the authorities were afraid to expose people to this diversity. Besides that, most European socialist countries enjoyed higher life standards and less ideological restrictions than Soviet Union.
Visits of foreigners to Soviet Union were severely restricted, their movements inside SU were also very much restricted (most foreigner were allowed to visit only Moscow and very few other principal cities), and many of them were under constant surveillance. The main reason was the same as in 1. Contacts of Soviet citizens with foreigners were limited and strictly controlled.
A very substantial number of people in the SU had the so-called "security clearance" ("dopusk" in Russian) connected with their jobs. When obtaining this clearance one had to sign an obligation to report to KGB on all their contacts with foreigners. If you had obtained a permission to travel abroad, after the travel you had to write a report and stand an interview with a KGB officer.
(All this is based on first-hand experience: I lived in the SU from the 1950s to the end of the 1980s.)
EDIT. Short comments on internal travel. Every citizen was equipped with an internal passport from the age of 16. This passport had a "residence registration" and was not valid without it. You could not freely change your residence registration: obtaining the registration from the local police was not a trivial matter, especially in large cities. One prerequisite was having a job in the city. On the other hand, hiring people who are not registered in this city was also prohibited. This created a "Catch 22" situation which very much restricted people's ability to move to another city. You could travel for short periods however: for stays of few days no registration was necessary. The purpose of this registration was to regulate the population of large cities where the life standard was higher than in small cities. Obtaining a residence registration in Moscow was almost impossible; a common way to obtain it was to marry a Moscovite:-)
The internal passport played the role of an ID (like a driver's license in the US) and in theory one had to carry it all the time. A policeman could request it to check your identity. Besides the residence registration and usual personal information the passport contained the data on your family state (spouse, children) and the weird piece of data called "nationality". (Russian, Ukrainian, Armenian, Greek, Jew, etc.) There was non-official discrimination against some "nationalities" in hiring and education.
Upvote:4
Regarding question 2, it should be noted that before a voyage to another country a Soviet citizen had to undergo a scrutiny by local Party organs, ostensibly to ensure his or her strict moral values. Some KGB checks were surely performed as well, but those were hidden. Questions by Party (Komsomol for younger people, I guess) were, on the contrary, open, and could be pretty humiliating in case of family matters, such as divorce. And a petty Party official had full authority to prevent you from visiting even Bulgaria, to say nothing of DDR.
By the way, while tourism abroad was rather rare, a considerable number of Soviet skilled persons went on business trips to friendly developing countries, such as Vietnam, Egypt, India, Cuba, to build or supervise plants, electrical stations and so on. They obviously had to undergo similar checks to tourists.
Travelling to the Western countries for leisure was unheard of. For business reasons (no need to remind that all business was state owned?) or cultural ties, probable but all checks were much stricter. And, as @jwenting mentioned, having a hostage of sorts was a huge plus. If a writer, for instance, went to France to receive an award from La Republique, going with his wife wasn't likely to be approved.
Upvote:10
This is not directly answering your question, but you might consider the German partition during the Cold War. This is illustrative because the Germans initially had open borders.
Upvote:13
They were so paranoid that those who were allowed to travel usually had to be married, preferably with children, and those would have to be left behind as hostages to guarantee their return under the implied threat of repercussions against them if the traveler decided to defect.
You still had to apply for an exit visa from the USSR (for example) as well as an entry visa to the other COMECON country which would generally only be granted if you had valid business there (iow, were traveling on government business).