Is it permissible to supplicate for the deceased by saying: "Astaghfirullah (I seek forgiveness from Allah), and Al-hamdulillah (all praise is due to Allah), and Allahu Akbar (Allah is the Greatest), and Walillahil Hamd (to Allah belongs all praise)," and then dedicating its reward to the deceased, or by giving charity and bestowing the reward of the charity upon him?

The first is to dedicate supplication and charity specifically for the deceased, as these benefit him without dispute. As for gifting the reward of dhikr (remembrance of Allah) to a deceased father, there is no objection to it. Some scholars have mentioned the permissibility for a Muslim to gift the reward of any act of worship to another Muslim, and that this benefits him by the permission of Allah.