JSP4563 You are correct.
It might be worth mentioning that BBs and AAs fire only once each combat and subs fires each round, to clear out any confusion for new players.
Are they any difference between LHTR and OOB rules ?
A lot of differences.
Mainly the LHTR are more clear, resolve some problems of the rules (for example the deployment of fighters on AC) and form a more rational set of rules.
What I can recall right now are the following points:
Clarification of the SBR and rocket attacks rules;
Introduction of the 9 city victory (Marginal Victory that is IMHO the more useful for face to face game);
Correction of the deployment rule of fighters on the AC.
Availability of Weapon development in the deplyment phase.
Correction of the National Advantages.
A good think to do is to read the thread that discuss of the LHTR rule. NAturally the best thing is download and use them!
See this thread for an in-depth discussion of the differences between the two rule sets.
where can you download the LHTR from?