So if i forgot to mention the tone of the second piece and didn't have time to analyse the last three chunks of the first article (still got down 4.5 pages), how severely will i be penalised?
As others have already alluded to the way English assessors mark your essays is not explicitly against a criteria sheet so making minor errors or omissions won't destroy your marks - it would actually be impossible for anyone to fully analyse anything within the timeframe so you are generally mostly marked on what you have written down (not what you have missed out on) obviously they want a proper structure though.
You won't be directly penalised for missing out on the tone/certain aspects of the article but if the omission takes away or you didn't analyse enough (in the opinion of the assessor) from your final piece you may not score as highly as you would if you had been able to include all that stuff.
How much will not finishing half of a paragraph for section B influence my score? I didn't get time to talk about one of the texts in the last paragraph! How much will this bring my score down??
See above.
Anecdotally I know some people who have got 50's without finishing their final paragraphs/not doing conclusion so if the rest of your essay is fine I wouldn't be too worried. Missing out on a little bit of 1 paragraph will not make the assessor disregard everything else you have written down.