We need to focus on the main point in the discussion.Iran won't be less reliable than Russia, sometimes you don't have many options, for example Iran is importing natural gas from Turkmenistan, they have shown to be anything but reliable but currently there are no other options for Iran; Iran can't afford to construct a whole delivery system and it is cheaper for Iran to stick with Turkmenistan gas (under current circumstances).
In order to understand how difficult and costly it is to build a natural gas delivery system read this article: How Does the Natural Gas Delivery System Work? - Natural Gas
What system are you talking about? The technology I'm talking about is no new system (as in yesterday's) All the modern refineries are using new technologies, at least majority of Iran's customers (India, China, Japan, Korea to name a few) which again are the MAIN importers of Iranian oil have the technology since 1982 and 1989 in India, Eastern European countries also have the technology however they're not an issue as they're not major importers. As a matter of fact the only country that faced problem was Sri Lanka which replaced Iran's oil with Iraq's oil to remedy the problem.
And yes the cost will be minimum. Certainly a lot less "minimum"than U.S. penalties, however even the countries that use older technologies (similar to that of Abadan's refinery) won't need to reconfigure their refineries as the Iraq's heavy crude could easily replace Iran's, however no country is willing to put aside diversification of its energy supplies and for a lesser cost at that to increase its dependencies on other countries.
As for your questions, if you read my post carefully as well as read the IMF report that I posted earlier should be sufficient to answer them.
Anyway, you have said sth like Iran cannot afford to build pipeline to NE to replace Turkmen gas, which it is wrong and even the construction of it is started 1-2 years ago. But, let's ignore non-important points.
Iran is obviously unreliable, and much much more unreliable than Russia. instead of getting emotional just note that 1)Iran has a crazy regime 2)Iran is a fully sanctioned country 3)Iran relations with EU have been cut throughly multiple times in the past 3-4 decades 4)Iran, can accidentally, climbs of other countries embassies in Tehran. 5)Iran has very very bad relations with its neighbors, and neighbors can cut the line whenever they want. 6)Iran-Turkey pipeline, which is the only gas export pipeline of Iran, is already bombed multiple times by PJAK, and PKK. 7)US would not be happy with it and would screw any possible attempts in this regard, and Iran has absolutely no power to not let US to do so. this is how oil is already sanctioned. 8)....
I can write more than 10 other reasons that why Iran is much much more unreliable than Russia, Azerbaijan, Turkmenistan, Qatar, KSA, Iraq, Egypt, and Algeria to supply EU gas.
