After going through the case history you have given your answers lie here,
1.Yes, if thier is infection in the pulp you need to undergo root canal treatment
2.Root canal treatment can be done in both single and multiple sittings,but it is advisable to go for multiple sittings since the pulp is infected.It includes the following steps ,
a.access opening of tooth
b.bmp ie.,cleaning and debridement.
c.obturation and access filling.
in these first step is done in first sitting and second and third steps can be done in either one or two sittings.
3.Once any infection might be due to caries from teeth surface or any abscess
from the periapical area affect pulp, Root canal treatment must be done.Their are alternatives if the infection would not have affected pulp.
4.Its better to get it done as early as possible,Yes you can wait for 2 months if the infection is in the initial level.
5.If the infection aggrevates or the pain continues its better to get it done, or if it susides by using the medication you can wait for some time.
Hope so this helps you,